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Circular Functions and Trigonometry workbook ~ categorized past IB Paper 1 and Paper 2 examination questions ~ IB DP Mathematics Standard Level Topic 3 This workbook contains past Paper 1 and Paper 2 IB examination questions categorized according to major concepts in this topic. Contents • 3.1 Graphs of Trigonometric Functions Paper 1 Questions 12 questions; 73 marks Paper 2 Questions 10 questions; 121 marks • 3.2 Arcs and Sectors Paper 1 Questions 13 questions; 68 marks Paper 2 Questions 5 questions; 57 marks • 3.3 Trigonometric Identities Paper 1 Questions 10 questions 61 marks Paper 2 Questions 11 questions; 75 marks • 3.4 Solution of Triangles Paper 1 Questions 2 questions 24 marks Paper 2 Questions 29 questions 284 marks page 1 page 8 page 18 page 24 page 28 page 33 page 40 page 42 The use of GDC is not permitted for Paper 1 but is required for Paper 2 questions. 3.1 Graphs of Trigonometric Functions 1. Paper 1 Consider g (x) = 3 sin 2x. (a) Write down the period of g. (1) (b) On the diagram below, sketch the curve of g, for 0 ≤ x ≤ 2π. (3) (c) Write down the number of solutions to the equation g (x) = 2, for 0 ≤ x ≤ 2π. (2) (Total 6 marks) y 4 3 2 1 0 –1 –2 –3 –4 2. π 2 π 3π 2 2π x The graph of a function of the form y = p cos qx is given in the diagram below. (a) Write down the value of p. (2) (b) Calculate the value of q. (4) (Total 6 marks) 1 3. A spring is suspended from the ceiling. It is pulled down and released, and then oscillates up and down. Its length, l centimetres, is modelled by the function l = 33 + 5cos((720t)°), where t is time in seconds after release. (a) Find the length of the spring after 1 second. (2) (b) Find the minimum length of the spring. (3) (c) Find the first time at which the length is 33 cm. (3) (d) What is the period of the motion? (2) (Total 10 marks) 2 4. The diagram below shows part of the graph of y = sin 2x. The shaded region is between x = 0 and x = m. (a) Write down the period of this function. (2) (b) Hence or otherwise write down the value of m. (2) (Total 4 marks) 5. x The diagram below shows the graph of f (x) = 1 + tan for −360° ≤ x ≤ 360°. 2 (a) On the same diagram, draw the asymptotes. (2) (b) Write down (i) the period of the function; (ii) the value of f (90°). (2) (c) Solve f (x) = 0 for −360° ≤ x ≤ 360°. (2) (Total 6 marks) 3 6. Let ƒ (x) = a sin b (x − c). Part of the graph of ƒ is given below. Given that a, b and c are positive, find the value of a, of b and of c. (Total 6 marks) 7. The graph of a function of the form y = p cos qx is given in the diagram below. (a) Write down the value of p. (b) Calculate the value of q. (Total 6 marks) y 40 30 20 10 π/2 π –10 –20 –30 –40 4 x 8. Consider y = sin x + π . 9 (a) The graph of y intersects the x-axis at point A. Find the x-coordinate of A, where 0 ≤ x ≤ π. (b) Solve the equation sin x + π = – 1 , for 0 ≤ x ≤ 2π. 2 9 (Total 6 marks) 9. Let f (x) = sin (2x + 1), 0 ≤ x ≤ π. (a) Sketch the curve of y = f (x) on the grid below. (b) Find the x-coordinates of the maximum and minimum points of f (x), giving your answers correct to one decimal place. (Total 6 marks) y 2 1.5 1 0.5 0 0.5 1 1.5 2 2.5 3 –0.5 –1 –1.5 –2 5 3.5 x 10. Part of the graph of y = p + q cos x is shown below. The graph passes through the points (0, 3) and (π, –1). Find the value of (a) p; (b) q. (Total 6 marks) y 3 2 1 0 π 2π x –1 11. The depth, y metres, of sea water in a bay t hours after midnight may be represented by the function 2π y = a + b cos t , where a, b and k are constants. k The water is at a maximum depth of 14.3 m at midnight and noon, and is at a minimum depth of 10.3 m at 06:00 and at 18:00. Write down the value of (a) a; (b) b; (c) k. (Total 4 marks) 6 12. The graph of y = p cos qx + r, for –5 ≤ x ≤ 14, is shown below. There is a minimum point at (0, –3) and a maximum point at (4, 7). (a) Find the value of (i) p; (ii) q; (iii) r. (6) (b) The equation y = k has exactly two solutions. Write down the value of k. (1) (Total 7 marks) 7 3.1 Graphs of Trigonometric Functions 1. Paper 2 Let f (x) = sin 2x and g (x) = sin (0.5x). (a) (b) Write down (i) the minimum value of the function f ; (ii) the period of the function g. Consider the equation f (x) = g (x). Find the number of solutions to this equation, for 0 ≤ x ≤ 3π . 2 (Total 6 marks) 2. Let f (x) = 6 sin πx , and g (x) = 6e–x – 3 , for 0 ≤ x ≤ 2. The graph of f is shown on the diagram below. There is a maximum value at B (0.5, b). (a) Write down the value of b. (b) On the same diagram, sketch the graph of g. (c) Solve f (x) = g (x) , 0.5 ≤ x ≤ 1.5. (Total 6 marks) y B 0 1 2 8 x 3. The following diagram represents a large Ferris wheel, with a diameter of 100 metres. Let P be a point on the wheel. The wheel starts with P at the lowest point, at ground level. The wheel rotates at a constant rate, in an anticlockwise (counterclockwise) direction. One revolution takes 20 minutes. (a) Write down the height of P above ground level after (i) 10 minutes; (ii) 15 minutes. (2) Let h(t) metres be the height of P above ground level after t minutes. Some values of h(t) are given in the table on the right. (b) (i) Show that h(8) = 90.5. (ii) Find h(21). (4) (c) Sketch the graph of h, for 0 ≤ t ≤ 40. (3) (d) Given that h can be expressed in the form h(t) = a cos bt + c, find a, b and c. (5) (Total 14 marks) 9 4. Let f(t) = a cos b (t – c) + d, t ≥ 0. Part of the graph of y = f(t) is given. When t = 3, there is a maximum value of 29, at M. When t = 9 , there is a minimum value of 15. (a) (i) Find the value of a. (ii) Show that b = (iii) Find the value of d. (iv) Write down a value for c. π . 6 (7) The transformation P is given by a horizontal stretch of a scale factor of (b) 1 , followed by a translation of 2 3 . −10 Let M′ be the image of M under P. Find the coordinates of M′. (2) The graph of g is the image of the graph of f under P. (c) Find g(t) in the form g(t) = 7 cos B(t – C) + D. (4) (d) Give a full geometric description of the transformation that maps the graph of g to the graph of f. (3) (Total 16 marks) 10 5. Let f(x) = (a) 3x x +1, g(x) = 4cos – 1. Let h(x) = (g ° f)(x). 2 3 Find an expression for h(x). (3) (b) Write down the period of h. (1) (c) Write down the range of h. (2) (Total 6 marks) 11 6. Let f(x) = 3sinx + 4 cos x, for –2π ≤ x ≤ 2π. (a) Sketch the graph of f. (3) (b) Write down (i) the amplitude; (ii) the period; (iii) the x-intercept that lies between − π and 0. 2 (3) (c) Hence write f(x) in the form p sin (qx + r). (3) (d) Write down one value of x such that f′(x) = 0. (2) (e) Write down the two values of k for which the equation f(x) = k has exactly two solutions. (2) (f) Let g(x) = ln(x + 1), for 0 ≤ x ≤ π. There is a value of x, between 0 and 1, for which the gradient of f is equal to the gradient of g. Find this value of x. (5) (Total 18 marks) 12 7. Let f(x) = 5 cos (a) π x and g(x) = –0.5x2 + 5x – 8, for 0 ≤ x ≤ 9. 4 On the same diagram, sketch the graphs of f and g. (3) (b) Consider the graph of f. Write down (i) the x-intercept that lies between x = 0 and x =3; (ii) the period; (iii) the amplitude. (4) (c) Consider the graph of g. Write down (i) the two x-intercepts; (ii) the equation of the axis of symmetry. (3) (Total 10 marks) 13 8. The following graph shows the depth of water, y metres, at a point P, during one day. The time t is given in hours, from midnight to noon. (a) Use the graph to write down an estimate of the value of t when (i) the depth of water is minimum; (ii) the depth of water is maximum; (iii) the depth of the water is increasing most rapidly. (3) (b) The depth of water can be modelled by the function y = A cos (B (t – 1)) + C. (i) Show that A = 8. (ii) Write down the value of C. (iii) Find the value of B. (6) (c) A sailor knows that he cannot sail past P when the depth of the water is less than 12 m. Calculate the values of t between which he cannot sail past P. (2) (Total 11 marks) 14 9. A formula for the depth d metres of water in a harbour at a time t hours after midnight is π d = P + Q cos t , 0 ≤ t ≤ 24, 6 d (12, 14.6) where P and Q are positive constants. In the 15 following graph the point (6, 8.2) is a minimum point and the point (12, 14.6) is a 10. maximum point. (a) Find the value of (i) Q; (ii) P. (6, 8.2) 5 0 6 12 24 t 18 (3) (b) Find the first time in the 24-hour period when the depth of the water is 10 metres. (3) (c) (i) Use the symmetry of the graph to find the next time when the depth of the water is 10 metres. (ii) Hence find the time intervals in the 24-hour period during which the water is less than 10 metres deep. (4) (Total 10 marks) 15 10. The diagram shows the graph of the function f given by f (x) = A sin π x + B, for 0 ≤ x ≤ 5, where A and B are 2 constants, and x is measured in radians. The graph includes the points (1, 3) and (5, 3), which are maximum points of the graph. y (5, 3) 2 (0, 1) x 0 (a) (1,3) Write down the values of f (1) and f (5). 1 2 3 5 4 (3, –1) (2) (b) Show that the period of f is 4. (2) The point (3, –1) is a minimum point of the graph. (c) Show that A = 2, and find the value of B. (5) (d) Show that f′ (x) = π cos π x . 2 (4) The line y = k – πx is a tangent line to the graph for 0 ≤ x ≤ 5. (e) Find (i) the point where this tangent meets the curve; (ii) the value of k. (6) (f) Solve the equation f (x) = 2 for 0 ≤ x ≤ 5. (5) (Total 24 marks) …continue on the next page 16 …continued from the previous page 17 3.2 Arcs and Sectors 1. Paper 1 The diagram shows two concentric circles with centre O. The radius of the smaller circle is 8 cm and the radius of π the larger circle is 10 cm. Points A, B and C are on the circumference of the larger circle such that AÔB is 3 radians. (a) Find the length of the arc ACB. (2) (b) Find the area of the shaded region. (4) (Total 6 marks) diagram not to scale 2. The following diagram shows a sector of a circle of radius r cm, and angle θ at the centre. The perimeter of the sector is 20 cm. 20 − 2r . r (a) Show that θ = (b) The area of the sector is 25 cm2. Find the value of r. (Total 6 marks) 18 3. The following diagram shows a circle with radius r and centre O. The points A, B and C are on the circle and 4 2 AÔC =θ. The area of sector OABC is π and the length of arc ABC is π. Find the value of r and of θ. 3 3 (Total 6 marks) 4. The diagram below shows a circle of radius r and centre O. The angle AÔB = θ. The length of the arc AB is 24 cm. The area of the sector OAB is 180 cm2. Find the value of r and of θ. (Total 6 marks) 19 5. The following diagram shows a circle of centre O, and radius r. The shaded sector OACB has an area of 27 cm2. Angle AÔB = θ = 1.5 radians. (a) Find the radius. (b) Calculate the length of the minor arc ACB. (Total 6 marks) A C B r O 6. The diagram below shows a circle of radius 5 cm with centre O. Points A and B are on the circle, and AÔB is 0.8 radians. The point N is on [OB] such that [AN] is perpendicular to [OB]. Find the area of the shaded region. (Total 6 marks) A 5 cm O 0.8 N 20 B 7. The diagram below shows a triangle and two arcs of circles. The triangle ABC is a right-angled isosceles triangle, with AB = AC = 2. The point P is the midpoint of [BC]. The arc BDC is part of a circle with centre A. The arc BEC is part of a circle with centre P. (a) Calculate the area of the segment BDCP. (b) Calculate the area of the shaded region BECD. (Total 6 marks) E B D P 2 A 8. C 2 The following diagram shows a circle of centre O, and radius 15 cm. The arc ACB subtends an angle of 2 radians at the centre O. Find (a) the length of the arc ACB; (b) the area of the shaded region. (Total 6 marks) C A B 15 cm Diagram not to scale 2 rad O AÔB = 2 radians OA = 15 cm 21 9. In the following diagram, O is the centre of the circle and (AT) is the tangent to the circle at T. If OA = 12 cm, and the circle has a radius of 6 cm, ﬁnd the area of the shaded region. (Total 4 marks) T O A diagram not to scale 10. The diagram below shows a sector AOB of a circle of radius 15 cm and centre O. The angle θ at the centre of the circle is 2 radians. (a) Calculate the area of the sector AOB. (b) Calculate the area of the shaded region. (Total 4 marks) B A O diagram not to scale 22 11. The diagram shows a circle of radius 5 cm. Find the perimeter of the shaded region. (Total 4 marks) 1 radian 12. O is the centre of the circle which has a radius of 5.4 cm. The area of the shaded sector OAB is 21.6 cm2. Find the length of the minor arc AB. (Total 4 marks) O B A 13. The diagrams show a circular sector of radius 10 cm and angle θ radians which is formed into a cone of slant height 10 cm. The vertical height h of the cone is equal to the radius r of its base. Find the angle θ radians. (Total 4 marks) 10cm 10cm h r 23 3.2 Arcs and Sectors 1. Paper 2 The circle shown has centre O and radius 3.9 cm. Points A and B lie on the circle and angle AOB is 1.8 radians. (a) Find AB. (3) (b) Find the area of the shaded region. (4) (Total 7 marks) diagram not to scale 2. The diagram below shows a circle centre O, with radius r. The length of arc ABC is 3π cm and AÔC = (a) 2π . 9 Find the value of r. (2) (b) Find the perimeter of sector OABC. (2) (c) Find the area of sector OABC. (2) (Total 6 marks) 24 A 3. The following diagram shows the triangle AOP, where OP = 2 cm, AP = 4 cm and AO = 3 cm. (a) diagram not to scale Calculate AÔP , giving your answer in radians. O The following diagram shows two circles which intersect at the points A and B. The smaller circle C1 has centre O and radius 3 cm, the larger circle C2 has centre P and radius 4 cm, and OP = 2 cm. The point D lies on the circumference of C1 and E on the circumference of C2.Triangle AOP is the same as triangle AOP in the diagram above. (b) (3) P A C2 C1 D O E P diagram not to scale Find AÔB , giving your answer in radians. (2) B (c) Given that AP̂B is 1.63 radians, calculate the area of (i) sector PAEB; (ii) sector OADB. (5) (d) The area of the quadrilateral AOBP is 5.81 cm2. (i) Find the area of AOBE. (ii) Hence find the area of the shaded region AEBD. (4) (Total 14 marks) 25 4. The following diagram shows two semi-circles. The larger one has centre O and radius 4 cm. The smaller one has centre P, radius 3 cm, and passes through O. The line (OP) meets the larger semi-circle at S. The semi-circles intersect at Q. (a) (i) Explain why OPQ is an isosceles triangle. (ii) Use the cosine rule to show that cos OP̂Q = (iii) Hence show that sin OP̂Q = (iv) Find the area of the triangle OPQ. 1 . 9 80 . 9 (7) (b) Consider the smaller semi-circle, with centre P. (i) Write down the size of OP̂Q. (ii) Calculate the area of the sector OPQ. (3) (c) Consider the larger semi-circle, with centre O. Calculate the area of the sector QOS. (3) (d) Hence calculate the area of the shaded region. (4) (Total 17 marks) 26 5. The diagram below shows a circle, centre O, with a radius 12 cm. The chord AB subtends at an angle of 75° at the centre. The tangents to the circle at A and at B meet at P. (a) Using the cosine rule, show that the length of AB is 12 2(1 – cos 75°) . (2) (b) Find the length of BP. (3) (c) Hence find (i) the area of triangle OBP; (ii) the area of triangle ABP. (4) (d) Find the area of sector OAB. (2) (e) Find the area of the shaded region. (2) (Total 13 marks) A 12 cm P diagram not to scale O 75º B 27 3.3 Trigonometric Identities 1. Paper 1 Solve the equation 2cos x = sin 2x, for 0 ≤ x ≤ 3π. (Total 7 marks) 2. The straight line with equation y = (a) 3 x makes an acute angle θ with the x-axis. 4 Write down the value of tan θ. (1) (b) Find the value of (i) sin 2θ; (ii) cos 2θ. (6) (Total 7 marks) 28 3. (a) Show that 4 – cos 2θ + 5 sin θ = 2 sin2 θ + 5 sin θ + 3. (2) (b) Hence, solve the equation 4 – cos 2θ + 5 sin θ = 0 for 0 ≤ θ ≤ 2π. (5) (Total 7 marks) 4. Solve cos 2x – 3 cos x – 3 – cos2 x = sin2 x, for 0 ≤ x ≤ 2π. (Total 7 marks) 29 5. Let f(x) = sin3 x + cos3 x tan x, (a) π < x < π. 2 Show that f(x) = sin x. (2) (b) Let sin x = 2 4 5 . Show that f(2x) = − . 3 9 (5) (Total 7 marks) 6. The following diagram shows a triangle ABC, where AĈB is 90°, AB = 3, AC = 2 and BÂC is θ. (a) Show that sin θ = 5 . 3 (b) Show that sin 2θ = 4 5 . 9 (c) Find the exact value of cos 2θ. (Total 6 marks) 30 7. Given that sin x = (a) cos x; (b) cos 2x. 1 , where x is an acute angle, find the exact value of 3 (Total 6 marks) 8. If A is an obtuse angle in a triangle and sin A = 5 , calculate the exact value of sin 2A. 13 (Total 4 marks) 31 9. Solve the equation 3 sin2 x = cos2 x, for 0° ≤ x ≤ 180°. (Total 4 marks) 10. (a) Given that 2 sin2 θ + sinθ – 1 = 0, find the two values for sin θ. (4) (b) Given that 0° ≤ θ ≤ 360° and that one solution for θ is 30°, find the other two possible values for θ. (2) (Total 6 marks) 32 3.3 Trigonometric Identities 1. The function f is defined by f : x → 30 sin 3x cos 3x, 0 ≤ x ≤ Paper 2 π . 3 (a) Write down an expression for f (x) in the form a sin 6x, where a is an integer. (b) Solve f (x) = 0, giving your answers in terms of π. (Total 6 marks) 2. Consider the trigonometric equation 2 sin2 x = 1 + cos x. (a) Write this equation in the form f (x) = 0, where f (x) = a cos2 x + b cos x + c, and a, b, c ∈ (b) Factorize f (x). (c) Solve f (x) = 0 for 0° ≤ x ≤ 360°. . (Total 6 marks) 33 3. Solve the equation 2 cos2 x = sin 2x for 0 ≤ x ≤ π, giving your answers in terms of π. (Total 6 marks) 4. (a) Write the expression 3 sin2 x + 4 cos x in the form a cos2 x + b cos x + c. (b) Hence or otherwise, solve the equation 3 sin2 x + 4 cos x – 4 = 0, 0° ≤ x ≤ 90°. (Total 4 marks) 34 5. (a) Express 2 cos2 x + sin x in terms of sin x only. (b) Solve the equation 2 cos2 x + sin x = 2 for x in the interval 0 ≤ x ≤ π, giving your answers exactly. (Total 4 marks) 6. Consider the equation 3 cos 2x + sin x = 1 (a) Write this equation in the form f (x) = 0 , where f (x) = p sin2 x + q sin x + r , and p , q , r ∈ (b) Factorize f (x). (c) Write down the number of solutions of f (x) = 0, for 0 ≤ x ≤ 2π. . (Total 6 marks) 35 7. Find all solutions of the equation cos 3x = cos (0.5x), for 0 ≤ x ≤ π. (Total 6 marks) 8. Solve the equation 3 cos x = 5 sin x, for x in the interval 0° ≤ x ≤ 360°, giving your answers to the nearest degree. (Total 4 marks) 36 9. (a) Factorize the expression 3 sin2 x – 11 sin x + 6. (b) Consider the equation 3 sin2 x – 11 sin x + 6 = 0. (i) Find the two values of sin x which satisfy this equation, (ii) Solve the equation, for 0° ≤ x ≤ 180°. (Total 6 marks) 37 10. (a) Consider the equation 4x2 + kx + 1 = 0. For what values of k does this equation have two equal roots? (3) Let f be the function f (θ ) = 2 cos 2θ + 4 cos θ + 3, for −360° ≤ θ ≤ 360°. (b) Show that this function may be written as f (θ ) = 4 cos2 θ + 4 cos θ + 1. (1) (c) Consider the equation f (θ ) = 0, for −360° ≤ θ ≤ 360°. (i) How many distinct values of cos θ satisfy this equation? (ii) Find all values of θ which satisfy this equation. (5) (d) Given that f (θ ) = c is satisfied by only three values of θ, find the value of c. (2) (Total 11 marks) 38 11. The diagram below shows a plan for a window in the shape of a trapezium. Three sides of the window are 2 m long. The angle between the sloping sides of the π window and the base is θ, where 0 < θ < . 2 (a) Show that the area of the window is given by y = 4 sin θ + 2 sin 2θ. (5) (b) Zoe wants a window to have an area of 5 m2. Find the two possible values of θ. (4) (c) John wants two windows which have the same area A but different values of θ. Find all possible values for A. (7) (Total 16 marks) 39 3.4 Solution of Triangles 1. Paper 1 The graph of the function f (x) = 3x – 4 intersects the x-axis at A and the y-axis at B. (a) (b) Find the coordinates of (i) A; (ii) B. Let O denote the origin. Find the area of triangle OAB. (Total 6 marks) 40 2. The following diagram shows a semicircle centre O, diameter [AB], with radius 2. Let P be a point on the circumference, with PÔB = θ radians. (a) Find the area of the triangle OPB, in terms of θ. (2) (b) Explain why the area of triangle OPA is the same as the area triangle OPB. (3) Let S be the total area of the two segments shaded in the diagram below. (c) Show that S = 2(π − 2 sin θ ). (3) (d) Find the value of θ when S is a local minimum, justifying that it is a minimum. (8) (e) Find a value of θ for which S has its greatest value. (2) (Total 18 marks) 41 3.4 Solution of Triangles 1. Paper 2 In the triangle PQR, PR = 5 cm, QR = 4 cm and PQ = 6 cm. Calculate (a) the size of PQ̂R ; (b) the area of triangle PQR. (Total 6 marks) 2. In triangle PQR, PQ is 10 cm, QR is 8 cm and angle PQR is acute. The area of the triangle is 20 cm2. Find the size of angle PQ̂R. (Total 6 marks) 42 3. In a triangle ABC, AB = 4 cm, AC = 3 cm and the area of the triangle is 4.5 cm2. Find the two possible values of the angle BÂC . (Total 6 marks) 4. The following diagram shows a triangle ABC, where BC = 5 cm, B̂ = 60°, Ĉ = 40°. (a) Calculate AB. (b) Find the area of the triangle. (Total 6 marks) A B 40° 60° 5 cm 43 C 5. Two boats A and B start moving from the same point P. Boat A moves in a straight line at 20 km h–1 and boat B moves in a straight line at 32 km h–1. The angle between their paths is 70°. Find the distance between the boats after 2.5 hours. (Total 6 marks) 6. In triangle ABC, AC = 5, BC = 7, Â = 48°, as shown in the diagram. Find B̂, giving your answer correct to the nearest degree. (Total 6 marks) C 5 A 48° 7 diagram not to scale B 44 7. The following diagram shows a triangle with sides 5 cm, 7 cm, 8 cm. Find (a) the size of the smallest angle, in degrees; (b) the area of the triangle. (Total 4 marks) 8. The diagrams below show two triangles both satisfying the conditions AB = 20 cm, AC = 17 cm, AB̂C = 50°. (a) Calculate the size of AĈB in Triangle 2. (b) Calculate the area of Triangle 1. (Total 4 marks) 45 9. Town A is 48 km from town B and 32 km from town C as shown in the diagram. Given that town B is 56 km from town C, find the size of angle CÂB to the nearest degree. (Total 4 marks) C 32km A B 48km 10. The diagram shows a vertical pole PQ, which is supported by two wires fixed to the horizontal ground at A and B. Find (a) the height of the pole, PQ; (b) the distance between A and B. (Total 4 marks) 46 11. A triangle has sides of length 4, 5, 7 units. Find, to the nearest tenth of a degree, the size of the largest angle. (Total 4 marks) 12. The following diagram shows triangle ABC. (a) AB = 7 cm, BC = 9 cm and AB̂C = 120°. Find AC. (3) (b) Find BÂC . (3) (Total 6 marks) 47 13. There is a vertical tower TA of height 36 m at the base A of a hill. A straight path goes up the hill from A to a point U. This information is represented by the following diagram. The path makes a 4° angle with the horizontal. The point U on the path is 25 m away from the base of the tower. The top of the tower is fixed to U by a wire of length x m. (a) Complete the diagram, showing clearly all the information above. (3) (b) Find x. (4) (Total 7 marks) 48 14. The diagram below shows a quadrilateral ABCD with obtuse angles AB̂C and AD̂C . AB = 5 cm, BC = 4 cm, CD = 4 cm, AD = 4 cm, BÂC = 30°, AB̂C = x°, AD̂C = y°. (a) Use the cosine rule to show that AC = 41− 40 cos x . (1) (b) Use the sine rule in triangle ABC to find another expression for AC. (2) (c) (i) Hence, find x, giving your answer to two decimal places. (ii) Find AC. (6) (d) (i) Find y. (ii) Hence, or otherwise, find the area of triangle ACD. (5) (Total 14 marks) 49 15. The diagram below shows a circle with centre O and radius 8 cm. The points A, B, C, D, E and F are on the circle, and [AF] is a diameter. The length of arc ABC is 6 cm. (a) Find the size of angle AOC. (2) (b) Hence find the area of the shaded region. (6) The area of sector OCDE is 45 cm2. (c) Find the size of angle COE. (2) (d) Find EF. (5) (Total 15 marks) 50 16. The following diagram shows the triangle ABC. The angle at C is obtuse, AC = 5 cm, BC = 13.6 cm and the area is 20 cm2. (a) Find AĈB . (4) (b) Find AB. (3) (Total 7 marks) diagram not to scale 17. The diagram below shows a triangle ABD with AB = 13 cm and AD = 6.5 cm. Let C be a point on the line BD such that BC = AC = 7 cm. (a) Find the size of angle ACB. (3) (b) Find the size of angle CAD. (5) (Total 8 marks) diagram not to scale 51 18. The following diagram shows a circle with centre O and radius 4 cm. The points A, B and C lie on the circle. The point D is outside the circle, on (OC). Angle ADC = 0.3 radians and angle AOC = 0.8 radians. (a) Find AD. (3) (b) Find OD. (4) (c) Find the area of sector OABC. (2) (d) Find the area of region ABCD. (4) (Total 13 marks) diagram not to scale 52 19. The diagram below shows triangle PQR. The length of [PQ] is 7 cm, the length of [PR] is 10 cm, and PQ̂R is 75°. (a) Find PQ̂R. (3) (b) Find the area of triangle PQR. (3) (Total 6 marks) diagram not to scale 20. A ship leaves port A on a bearing of 030°. It sails a distance of 25 km to point B. At B, the ship changes direction to a bearing of 100°. It sails a distance of 40 km to reach point C. This information is shown in the diagram below. A second ship leaves port A and sails directly to C. (a) Find the distance the second ship will travel. (4) (b) Find the bearing of the course taken by the second ship. (3) (Total 7 marks) 53 21. A farmer owns a triangular field ABC. One side of the triangle, [AC], is 104 m, a second side, [AB], is 65 m and the angle between these two sides is 60°. (a) Use the cosine rule to calculate the length of the third side of the field. (3) (b) Given that sin 60°= 3 , find the area of the field in the form 3 p 3 where p is an integer. 2 (3) Let D be a point on [BC] such that [AD] bisects the 60° angle. The farmer divides the field into two parts A1 and A2 by constructing a straight fence [AD] of length x metres, as shown on the diagram below. (c) 65x . 4 (i) Show that the area of A1 is given by (ii) Find a similar expression for the area of A2. (iii) Hence, find the value of x in the form q 3 , where q is an integer. (7) (d) (i) Explain why sinAD̂C = sinAD̂B . (ii) Use the result of part (i) and the sine rule to show that BD 5 = . DC 8 (5) (Total 18 marks) 54 22. The following diagram shows a pentagon ABCDE, with AB = 9.2 cm, BC = 3.2 cm, BD = 7.1 cm, AÊD =110°, AD̂E = 52° and AB̂D = 60°. (a) Find AD. (4) (b) Find DE. (4) (c) The area of triangle BCD is 5.68 cm2. Find DB̂C . (4) (d) Find AC. (4) (e) Find the area of quadrilateral ABCD. (5) (Total 21 marks) 55 23. The diagram below shows a quadrilateral ABCD. AB = 4, AD = 8, CD =12, B Ĉ D = 25°, BÂD =θ. (a) Use the cosine rule to show that BD = 4 5 − 4 cos θ . (2) Let θ = 40°. (b) (i) Find the value of sin CB̂D . (ii) Find the two possible values for the size of CB̂D . (iii) Given that CB̂D is an acute angle, find the perimeter of ABCD. (12) (c) Find the area of triangle ABD. (2) (Total 16 marks) 56 24. (a) Let y = –16x2 + 160x –256. Given that y has a maximum value, find (i) the value of x giving the maximum value of y; (ii) this maximum value of y. The triangle XYZ has XZ = 6, YZ = x, XY = z as shown below. The perimeter of triangle XYZ is 16. (4) (b) (i) Express z in terms of x. (ii) Using the cosine rule, express z2 in terms of x and cos Z. (iii) Hence, show that cos Z = 5 x −16 . 3x (7) Let the area of triangle XYZ be A. (c) Show that A2 = 9x2 sin2 Z. (2) (d) Hence, show that A2 = –16x2 + 160x – 256. (4) (e) (i) Hence, write down the maximum area for triangle XYZ. (ii) What type of triangle is the triangle with maximum area? (3) (Total 20 marks) 57 25. The diagram shows a triangular region formed by a hedge [AB], a part of a river bank [AC] and a fence [BC]. The hedge is 17 m long and BÂC is 29°. The end of the fence, point C, can be positioned anywhere along the river bank. (a) Given that point C is 15 m from A, find the length of the fence [BC]. (3) (b) The farmer has another, longer fence. It is possible for him to enclose two different triangular regions with this fence. He places the fence so that AB̂C is 85°. (i) Find the distance from A to C. (ii) Find the area of the region ABC with the fence in this position. (5) (c) To form the second region, he moves the fencing so that point C is closer to point A. Find the new distance from A to C. (4) (d) Find the minimum length of fence [BC] needed to enclose a triangular region ABC. (2) (Total 14 marks) 15 m A river bank C 29° 17 m B 58 26. 7 10 The diagram shows a parallelogram OPQR in which OP = , OQ = . 3 1 (a) Find the vector OR . (3) (b) Use the scalar product of two vectors to show that cos OP̂Q = – 15 . 754 (4) (c) (i) Explain why cos PQ̂R = –cos OP̂Q. (ii) Hence show that sin PQ̂R = (iii) Calculate the area of the parallelogram OPQR, giving your answer as an integer. 23 754 . (7) (Total 14 marks) y P Q O x R 59 27. The points P, Q, R are three markers on level ground, joined by straight paths PQ, QR, PR as shown in the diagram. QR = 9 km, PQ̂R = 35°, PR̂Q = 25°. P diagram not to scale Q (a) 35° 25° 9 km R Find the length PR. (3) (b) Tom sets out to walk from Q to P at a steady speed of 8 km h–1. At the same time, Alan sets out to jog from R to P at a steady speed of a km h–1. They reach P at the same time. Calculate the value of a. (7) (c) The point S is on [PQ], such that RS = 2QS, as shown in the diagram. P S Q R Find the length QS. (6) (Total 16 marks) 60 28. The diagram shows a triangle ABC in which AC = 7 2 , BC = 6, AB̂C = 45°. 2 A 2 7 2 Diagram not to scale B (a) Use the fact that sin 45° = 45° C 6 6 2 to show that sin BÂC = . 7 2 (2) The point D is on (AB), between A and B, such that sin BD̂C = (b) (i) Write down the value of BD̂C + BÂC . (ii) Calculate the angle BCD. (iii) Find the length of [BD]. 6 . 7 (6) (c) Show that Area of ∆BDC BD = . BA Area of ∆BAC (2) (Total 10 marks) 61 29. In the diagram below, the points O(0, 0) and A(8, 6) are ﬁxed. The angle OP̂A varies as the point P(x, 10) moves along the horizontal line y = 10. (a) (i) Show that AP = x 2 – 16 x + 80. (ii) Write down a similar expression for OP in terms of x. (2) (b) Hence, show that cos OP̂A = x 2 – 8 x + 40 √ {( x 2 – 16 x + 80)( x 2 + 100)} , (3) (c) Find, in degrees, the angle OP̂A when x = 8. (2) (d) Find the positive value of x such that OP̂A = 60° . (4) Let the function f be deﬁned by f ( x) = cos OP̂A = (e) x 2 – 8 x + 40 √ {( x 2 – 16 x + 80)( x 2 + 100)} , 0 ≤ x ≤ 15. Consider the equation f (x) = 1. (i) Explain, in terms of the position of the points O, A, and P, why this equation has a solution. (ii) Find the exact solution to the equation. (5) (Total 16 marks) y P(x, 10) y=10 A(8, 6) O(0, 0) x diagram to scale 62