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Right Triangle Trigonometry: Word Splash Use your prior knowledge or make up a meaning for the following words to create a story. Use your imagination! Relating to the Real World • Before any spacecraft ever traveled to another planet, astronomers had figured out the distance from each planet to the sun. They accomplished this feat by using trigonometry the mathematics of triangle measurement. You will learn how to use trigonometry to measure distances that you could never otherwise measure. Measure for Measure • What do the Trigonometric Ratios tell you about the parts of a triangle? • What are the conditions for triangles to be similar? • How can you remember the Trigonometric ratios? Label These Two Triangles Angle A Angle A The Tangent Ratio • The word Trigonometry comes from the Greek words meaning “triangle measurement.” A ratio of the lengths of sides of a right triangle. This ratio is called the TANGENT. • TANGENT OF A = leg opposite A leg adjacent to A • Slope of a line = Rise Run Using the Tangent Ratio • Tangent of < A = Leg OPPOSITE TO < A Leg ADAJACENT TO <A B THIS EQUATION CAN BE ABBREVIATED AS: Leg Opposite to < A, BC TAN A = OPPOSITE = BC A C Leg Adjacent to < A, CA ADJACENT CA Example Write the Tangent Ratios for < U and < T. T Tan U = opposite = TV = 3 adjacent UV 4 5 Tan T = opposite = UV = 4 adjacent TV 3 3 V 4 U Try This • Write the Tangent ratios for < K and < J • How is Tan K related to the Tan J ? J 3 K L 7 Try This: Find the Tangent of < A to the nearest tenth 1. 2. 4 A 8 5 A Hint: Find the Ratio First! 4 Practice: • Find the Tan A and Tan B ratios of each triangle. B 5 5 3 4 2 B A A 4 B 7 B 6 A 5 A 10 Using the Sine Ratio • Sine of < A = Leg OPPOSITE TO < A Hypotenuse B THIS EQUATION CAN BE ABBREVIATED AS: Leg Opposite to < A, BC Sin A = OPPOSITE = BC HYPOTENUSE AB A C Sin B = OPPOSITE = Leg Opposite to < B, CA CA HYPOTENUSE AB Example Write the Sine Ratios for < U and < T. T Sin U = opposite = TV = 3 hypotenuse TU 5 5 Sin T = opposite = UV = 4 hypotenuse TU 5 3 V 4 U Try This • Write the Sine ratios for < K and < J J 10 6 K L 8 Practice: • Find the Sin A and Sin B ratios of each triangle. B 4 5 3 4 2 B A A 5 B 7 B 8 A 7 A 10 Using the Cosine Ratio • Cosine of < A = Leg Adjacent TO < A Hypotenuse B THIS EQUATION CAN BE ABBREVIATED AS: Leg Adjacent to < B, BC Cos A = ADJACENT = CA HYPOTENUSE AB A C Cos B = ADJACENT = BC Leg Adjacent to < A, CA HYPOTENUSE AB Example Write the Cosine Ratios for < U and < T. T Cos U = adjacent = UV = 4 hypotenuse TU 5 5 Cos T = adjacent = TV = 3 hypotenuse TU 5 3 V 4 U Try This • Write the Cosine ratios for < K and < J J 10 6 K L 8 Practice: • Find the Cos A and Cos B ratios of each triangle. B 4 5 3 4 2 B A A 5 B 7 B 6 A 5 A 10 Finding Angles • To Find an angle use the inverse function of your calculator. B You may use the Leg Opposite to < A, BC A C Leg Adjacent to < A, CA Sin-1 Cos-1 or Tan-1 to find any angle. Practice: • Use the Cos-1 and Sin -1 ratios to find the angles of each triangle. B 5 6 3 4 2 B A A B 7 B 6 A 7 A 10