Paper 1 Things to Learn Off Algebra – Difference and Sum of Cubes ๐ฅ 3 − ๐ฆ 3 = ๐ฅ − ๐ฆ ๐ฅ 2 + ๐ฅ๐ฆ + ๐ฆ 2 ๐ฅ 3 + ๐ฆ 3 = ๐ฅ + ๐ฆ ๐ฅ 2 − ๐ฅ๐ฆ + ๐ฆ 2 Forming a Quadratic ๐ฅ 2 − sum of roots ๐ฅ + (product of roots) = 0 Nature or Roots Real ๐ 2 − 4๐๐ ≥ 0 Equal ๐ 2 − 4๐๐ = 0 No Real Roots ๐ 2 − 4๐๐ < 0 Factor Theorem (understand NOT prove) If ๐ฅ − ๐ is a factor of ๐(๐ฅ) then ๐ฅ = ๐ is a root. Binomial Theorem ๐ ๐ ๐−๐ ๐ ๐ฅ+๐ฆ ๐ =เท ๐ฅ ๐ฆ ๐ the most important topic and the largest. Every topic contains Algebra. ๐=0 Topics • • • • • • • • • • • • • Substitution Rearrange (Manipulate) Formula Expand Expressions (including large powers using Binomial) Factorising Algebraic Expressions & Simplify Simplify Algebraic Fractions Form Algebraic Expressions (Word Problems) Rationalise the Denominator Algebraic Identities Nature of Roots Use the Factor Theorem Quadratic Factor of a Cubic Function Prove Abstract Inequalities Form Quadratic/ Cubic Equations Given Roots Above formula (in tables) is for the ๐ + 1 term. Complex Numbers – De Moivre’s Proof by Induction De Moivre’s to Prove Trigonometric Identities The use of imaginary numbers. ๐ = −1 Polar Form ๐ง = ๐ cos ๐ + ๐ sin ๐ If ๐ง = ๐ฅ + ๐๐ฆ • then the modulus ๐ = ๐ง = ๐ฅ 2 + ๐ฆ 2 and the argument ๐ is found using the tan ratio. • • • • • • Conjugate Roots Theorem Let ๐๐ง 2 + ๐๐ง + ๐ = 0 be a quadratic equation. If ๐ง1 is a root then so is its conjugate ๐ง1าง Not valid for ๐’s in the coefficients of ๐ง. • • • • Number & Arithmetic – Proof By Contradiction ( ๐ is irrational) Construction of ๐ and ๐ • Very small but practical section. Commutative → ๐ + ๐ = ๐ + ๐ Associative → ๐ + ๐ + ๐ = ๐ + ๐ + ๐ Distributive → ๐ ๐ + ๐ = ๐๐ + ๐๐ Lots of Algebra and Trigonometry Error Error = Accurate − Observed Error Relative Error = Accurate Value Error Percentage Error = × 100 Accurate Value • • • • • • • Addition, Subtraction, Multiplication in Rectangular form. Conjugate of a Complex Number Division using the Complex Conjugate Argand Diagram – Plotting and Reading Transformations of Complex Numbers Modulus of a Complex Number Polar Form – Finding Modulus (Distance to Origin) and Argument (Angle) Multiplication and Division in Polar form. Solve quadratic equation with complex roots. Conjugate Roots Theorem Complex Identities Types of Number • (๐, ๐, ๐, ๐ , ๐ /๐, ๐ถ) Commutative/ Associative/ Distributive Rules Order of Operations Percentages/ Fractions/ Decimals Factors and Multiples Product of Primes Ratio and Proportion Order of Magnitude Topics • • • • • • • • • • • • • • • • Solve Linear Equations Solve Equations with Surds Solve Indices Equations (Rules in Tables) Solve Logarithmic Equations (Rules in Tables) Solve Irrational Equations Solve Quadratic Equations Solve Cubic Equations Solve Inequalities Solve Compound Inequalities Solve Rational Inequalities Solve Modulus Equations Solve Modulus Inequalities Solve Simultaneous Equations (2 variable – linear) (2 variable – linear & non linear) (3 variable – linear) • De Moivre’s Theorem to find Higher Powers ๐ง = ๐ cos ๐ + ๐ sin ๐ then ๐ง 3 = ๐ 3 cos 3๐ + ๐ sin 3๐ • De Moivre’s Theorem to find Roots ๐ง 3 = ๐ cos ๐ + ๐ sin ๐ then 1 1 1 ๐ง = ๐ 3 cos ๐ + 2๐๐ + ๐ sin ๐ + 2๐๐ 3 3 ๐ = 0, ๐ = 1, ๐ = 2 • Roots of Unity • Proof by Induction of De Moivre’s • De Moivre’s to Prove Trigonometric Identities • • • • • • • • • Estimation and Rounding Scientific Notation Construction of 2 and 3 Proof by Contradiction ( 2 is irrational) Accumulated Error Percentage Error Tolerance Average Rates of Change Metric vs Imperial Paper 1 Things to Learn Off Topics Patterns (Sequences and Series) – Sum of a Geometric Series By Induction Sum to Infinity if Geometric Series (using Limits) General Sequence Notation ๐๐ = 4๐ + 3 General Series Notation Adds formulae to the practical methods we used in Junior Cert questions. Lots of little things to learn and lots of Algebra. Proof by Induction can be very tricky and requires lots of practice. Financial Maths – Small but tricky section. Need good Sequences and Series and Algebra skills. Proof by Induction ๐=1 ๐=๐ ๐ =๐+1 Arithmetic Sequence ๐ = ๐3 − ๐2 = ๐2 − ๐1 ๐๐ = ๐๐ − ๐๐−1 Geometric Sequence ๐3 ๐= ๐2 ๐๐ = ๐๐ − ๐๐−1 Quadratic Sequence – General Term A quadratic sequence will be in the form ๐๐ = ๐๐2 + ๐๐ + ๐ 2nd Difference = 2๐ Generate Amortisation Formula using Sum of Geometric Series % Profit (Mark-Up) Profit/Loss = × 100 Cost Price % Profit (Margin) Profit = × 100 Selling Price Tax Gross Tax = Standard Tax + Higher Tax Tax Payable = Gross Tax – Tax Credit Net Income = Gross Income – Tax Payable Area and Volume – Trapezoidal Rule (only new learning from JC) Generally a part of other Q’s. Area ≈ h First + Last + 2(Rest) 2 Topics 4 Proof By Induction: เท ๐๐ = ๐1 + ๐2 + ๐3 + ๐4 3 Types ๐=1 Arithmetic Sequences and Series (formula in tables) ๐๐ = ๐ + ๐ − 1 ๐ ๐ ๐๐ = 2๐ + ๐ − 1 ๐ 2 • (Divisibility) • (Series) • (Inequalities) Reoccurring Sequences Geometric Sequences and Series (formula in tables) ๐๐ = ๐๐ ๐−1 ๐ 1 − ๐๐ ๐๐ = 1−๐ ๐ ๐∞ = for ๐ < 1 1.54แถ 7แถ = 1.54747474747 … = 1+ 5 47 47 + + +โฏ 10 1000 100000 1−๐ Quadratic Sequences and Series (see left) • • • • • Compound Interest (formula in tables) Depreciation (formula in tables) Present Value (rearrange compound formula) Loan Repayments (can use amortisation formula) Investments (savings) Present Value of Loan Repayments ๐ด ๐ด ๐ด ๐ด = + + + โฏ+ 1+๐ 1 1+๐ 2 1+๐ 3 1+๐ Future Value of Instalment Savings = ๐ 1 + ๐ ๐ก + ๐ 1 + ๐ ๐ก−1 + โฏ + ๐ 1 + ๐ ๐ก 1 Nets of Prisms, Cylinders and Cones Perimeter of circle, triangle, rectangle, square, parallelogram, trapezium, sectors of discs, and figures made from combinations of these. Trapezoidal rule to approximate area. • • • • • • • Profit/ Loss Discount Selling Price Mark Up and Margin Income Tax Net Pay Costing & Materials Use of Geometric Formula ๐ 1 − ๐๐ ๐๐ = 1−๐ Surface area and volume of the following solid figures: rectangular block, cylinder, right cone, triangular-based prism (right angle, isosceles and equilateral), sphere, hemisphere, and solids made from combinations of these. Paper 1 Functions and Graphs – Need excellent algebra skills. Generally asked through real world scenarios. Often linked with Calculus below. Things to Learn Off Injective Functions (one to one) Every output is the image of a unique input. Horizontal Line Test – any horizontal line drawn will never cut the graph at more than one point. Surjective Functions (onto) Every element in the co-domain is an output. Horizontal Line Test – every horizontal line intersects the graph of ๐ at at least one point. Bijective Functions (one to one & onto) Both injective and surjective. Trigonometric Functions ๐ ๐ฅ = ๐sin ๐๐ฅ ๐(๐ฅ) = ๐cos ๐๐ฅ ๐๐๐ง๐ ๐ −๐, ๐ ๐๐๐ซ๐ข๐จ๐ = 2๐ ๐ Vertical Asymptote Bottom = 0 Horizontal Asymptote ๐ฆ = lim ๐ ๐ฅ Topics • continuation of functions and graphs. All about ‘Rates of Change’. Calculus Integration – The reverse of differentiation. Differentiation from 1st Principles ๐ ๐ฅ = ๐ ๐ฅ+โ = ๐ ๐ฅ+โ −๐ ๐ฅ = ๐ ๐ฅ+โ −๐ ๐ฅ = โ ๐ ๐ฅ+โ −๐ ๐ฅ lim = โ→0 โ Differentiation Rules are in the Tables Notation • Linear Functions • Domain, Codomain, Range • Quadratic Functions • Vertical Line Test for a Function • Cubic Functions • Forming Polynomial Function given the roots. • Exponential Functions • Composite Functions • Logarithmic Functions • Inverse Functions • Trigonometric Functions • Injective, Surjective, Bijective Functions • Modular Functions • Limit of a Function • Continuity • Asymptotes ๐ ๐ Integration Rules are in the Tables • • • • • • • • • • Differentiation by Rule Product Rule (in tables) Quotient Rule (in tables) Chain Rule Differentiation from 1st Principles Trigonometric Differentiation Logarithmic Differentiation Exponential Differentiation 2nd and 3rd Derivatives • Idea that integration is the reverse of differentiation Definite vs Indefinite Integrals (constant of integration ๐) Integrate functions of the form: • ๐ฅ ๐ , ๐ ๐ฅ , sin ๐๐ฅ , cos ๐๐ฅ. Find areas bounded by curves. Find the average value of a function. • • • • Graphs of the 1st and 2nd Derivatives of Functions (see differentiation) • Average Value 1 เถฑ ๐(๐ฅ) ๐๐ฅ ๐−๐ Sketching the Graphs and Transformations of: • ๐ฅ→∞ Calculus Differentiation - Very much a Topics Completing the Square Differentiate to find: • Slopes of tangents (lines) to functions. • Gradient • Tangent to a Circle. • Stationary/ Turning Points (Max and Min). • Points of Inflection. • Increasing and decreasing functions. • Rate of Change. • Related Rates of Change. • Distance→ Speed → Acceleration Integrate to find: • Areas Bounded by Curves. • The Average Value of a Function. • Anti-Derivatives. • The function given its slope. • Acceleration → Speed → Distance Paper 2 Things to Learn Off Things to Learn Off Topics Probability – Both Statistics and Probability tend to have less Algebra than some of the other topics (though not always). The downside is that they are both large sections with a good bit to learn off. There is a bit of crossover with inferential statistics being as much probability as statistics. Margin of Error for a Population Proportion (95%) In OR events we ADD the probabilities ๐ ๐ด ∪ ๐ต = ๐ ๐ด ๐๐ ๐ต ๐ ๐ด ∪ ๐ต = ๐ ๐ด + ๐ ๐ต − ๐(๐ด ∩ ๐ต) In AND events we MULTIPLY the probabilities ๐ ๐ด ∩ ๐ต = ๐(๐ด ๐๐๐ ๐ต) ๐ ๐ด ∩ ๐ต = ๐ ๐ด). ๐(๐ต Mutually Exclusive events have no outcomes in common. Events that CANNOT occur at the same time. ๐ ๐ด ∪ ๐ต = ๐ ๐ด + ๐(๐ต) Independent events are where the outcome of the 1st does NOT affect the outcome of the second. ๐ ๐ด ∩ ๐ต = ๐ ๐ด). ๐(๐ต Conditional Probability ๐ ๐ด∩๐ต ๐ ๐ด๐ต = ๐(๐ต) Bernoulli Trial There are two outcomes: success or failure The trials are independent. The probability of success does not change from one trial to another. ๐ ๐ ๐−๐ ๐ ๐ ๐ ๐ = probability of success ๐ = probability of failure ๐ = number of trials ๐ = number of desired outcomes Expected Value E(X) is the average outcome of an event ๐ธ ๐ = σ ๐ฅ. ๐(๐ฅ) To find expected value we multiply every possible outcome by the probability for that outcome and then add all these values together. = ±1.96 ๐เท 1 − ๐เท ๐ • Sample Spaces – Listing Outcomes • Fundamental Principal of Counting • Arrangements (Permutations) • Combinations • Probability • Relative Frequency Confidence Interval of Sample Mean at 5% Level of Significance ๐ ๐ ๐ฅาง − 1.96 < ๐ < ๐ฅาง + 1.96 ๐ ๐ • Expected Frequency • Sets and Venn Diagrams • AND/ OR Central Limit Theorem When we are dealing with a simple random sample from a population we must adjust the standard deviation and z-score. Applies when: ๐ > 30 (for any population, normal or otherwise). ๐ ≤ 30 (if the underlying population is normal). The mean of the sampling distribution of the sample mean is equal to the population mean. • Mutually Exclusive • Expected Value • Fair Games • Bias • Independent • Conditional Probability • Probability of 2 Events • Bernoulli Trial 95% Confidence Interval for a Proportion ๐เท 1 − ๐เท ๐เท 1 − ๐เท ๐เท − 1.96 < ๐ < ๐เท + 1.96 ๐ ๐ Margin of Error for a Sample Means (95%) ๐ ๐ธ = +1.96 ๐ ๐ ๐ฅาง = ๐ The standard deviation of the sampling distribution of the sample mean (the standard error of the mean) is • Sampling Distributions ๐ ๐ ๐ฅาง = ๐ • The Normal Distribution & z-scores • Margin of Error In the above case the corresponding z-score for the sample mean is • Confidence Interval • Hypothesis Testing ๐ฅาง − ๐ ๐ง= ๐ ๐ The above is a joint Statistics/ Probability section. Paper 2 Things to Learn Off Things to Learn Off Topics Statistics – Population – is the entire group being studied Census – is a survey of the whole population Sample – is a group that is selected from the population Parameter – is a numerical measurement describing some characteristic of a population. Statistic – is a numerical measurement describing some characteristic of a sample. Simple random sample – selected a sample of size n, in such a way that every sample of size n has an equal chance of being selected. Stratified random sample – first divide population into subgroups so that individuals within each subgroup share characteristics. Then a sample random sample is drawn from each group. Eg. We might first divide population by gender. Systematic random sample – We select the sample based on random starting point and select a fixed periodic interval. Eg Select every 5th entry. Cluster sample – population is divided by sections or clusters. Then some of those clusters are randomly selected and all members from those clusters are chose. Eg. We want a sample of students. We get a list of schools and then select a school and use those students. Quota sample – Non probability sampling. We select to fill a quota of a certain type of subgroup. Eg Selecting men between age 30 and 40. Convenience sample – selecting group of people as it was easy to contact them. Eg. Selecting 20 people by taking the first 20 names on a register. Descriptive Statistics – summarise and present data so that people can easily understand. Inferential Statistics – predict or forecast based on responses of a sample group. Control Group - The control group in an experiment is the group who does not receive any treatment and is used as a benchmark against which other test results are measured. Explanatory variable – controlled variable Response variable – the effect being observed Commentating on Graphs • Continuation of much of the Junior Cert course where students analyse and graph data. Long questions generally combine the topics of Statistics and Probability, in particular areas concerning the normal distribution and z-scores, confidence intervals, margin of error and hypothesis testing. • Quote the range of the data. • Can we estimate the mean? Is the mode obvious? • Comment on standard deviation of the data. Large standard deviation means the data is well spread. Low standard deviation gives more of a cluster. Are there any outliers. • We use a scatter graph when we have data that can be paired together (bivariate data). An example would be heights and weights or age and salary. We measure how well they are related through Correlation. A line of best fit is one that comes as close as possible to the points. We can find the equation of this line by selecting two points on the graph and using co-ordinate geometry. Describing the distribution • Normal Distribution, symmetrical, bell curve • Skewed left or negatively skewed (your left foot) • Skewed right or positively skewed (your right foot) The Empirical rule states that in any Normal distribution: 68% of the population lie within one standard deviation of the mean ๐ฅาง − ๐, ๐ฅาง + ๐ 95% of the population lie within two standard deviations of the mean ๐ฅาง − 2๐, ๐ฅาง + 2๐ 99.7% of the population lie within three standard deviations of the mean ๐ฅาง − 3๐, ๐ฅาง + 3๐ • • • • • • • • • • • • • • • • • • • Central Tendencies • Mean • Mode • Median Mean of a Frequency Distribution Grouped Frequency Distributions (MidInterval) Measures of Spread • Range • Interquartile Range • Standard Deviation • Outliers Describe Shape of Distribution Relative Standing – Percentiles Stem and Leaf Diagram Bar Chart Pie Chart Line Graph Histogram Scatter Plot Correlation Coefficient Line of Best Fit Types of Surveys (Advantages/ Disadvantages) Misuse of Statistics The Normal Distribution Margin of Error Confidence Interval Hypothesis Testing Types of Data • Numerical • Categorical • Discrete • Continuous • Nominal • Ordinal • • Primary Secondary • • Univariate Bivariate Paper 2 Things to Learn Off The Line – Line in the form ๐๐ + ๐๐ + ๐ = ๐ Continues learning from the Junior Cert adding more formulae, most of which are in the tables. Need good Algebra and Geometry! Things to Learn Off Perpendicular Slope Turn the slope upside down and change the sign. 3 If a line has a slope of the perpendicular slope We can find: where it crosses the ๐ axis by letting ๐ฆ=0 where it crosses the ๐ axis by letting ๐ฅ=0 (also do this to draw a line) 5 5 is − 3 To prove slopes perpendicular ๐1 ๐2 = −1 Parallel Slope If lines are parallel then the slopes are equal the slope ๐, using ๐ − ๐ if a point is on the line by subbing the values of the point ๐ฅ1 , ๐ฆ1 in for ๐ฅ and ๐ฆ. Parallel Lines If ๐๐ฅ + ๐๐ฆ + ๐ = 0 is a line then a parallel line can be written ๐๐ฅ + ๐๐ฆ + ๐ = 0 A perpendicular line can be written ๐๐ฅ − ๐๐ฆ + ๐ = 0 Line in the form ๐ = ๐๐ + ๐ ๐ will be the slope ๐๐๐ ๐ 3 ๐= = ๐๐ข๐ 4 Lines Parallel to the Axes ๐ฅ = 2 is a line parallel to the ๐ฆ-axis through 2 on the ๐ฅ axis ๐ฆ = −1 is a line parallel to the ๐ฅ-axis through − 1 on the ๐ฆ axis ๐ the ๐ฆ-intercept (the place where the line crosses ๐ฆ axis) The Circle – Uses most of the formulae from the line adding just the ‘Equation of a Circle’ formulae. Need good Algebra and Geometry! Equation of circle with centre (๐, ๐) and radius ๐ ๐ฅ − โ 2 + ๐ฆ − ๐ 2 = ๐2 Circles touch Internally If circles touch internally the difference of their radii will equal the distance between their centres. General Equation of a circle ๐ฅ 2 + ๐ฆ 2 + 2๐๐ฅ + 2๐๐ฆ + ๐ = 0 1 2 Centre is (−๐, −๐) which is the coefficient of ๐ฅ 1 2 and the coefficient of ๐ฆ Radius is ๐2 + ๐2 − ๐, providing Circles touch Externally ๐ = ๐1 + ๐2 If circles touch externally the sum of their radii will equal the distance between their centres. ๐2 + ๐2 −๐ >0 ๐ = ๐1 − ๐2 Circles touching the x-axis ๐2 = ๐ Circles touching the y-axis ๐2 = ๐ Topics From Junior Cert • Distance between two points (in tables) • Finding Slopes • with slope formula (in tables) • with ๐ฆ = ๐๐ฅ + ๐ (in tables) • with rise over the run • Equation of a Line (in tables) • Intersection of 2 Lines • Line intersecting axis New For Leaving Cert • Angle Between Lines (in tables) • Area of a Triangle (in tables) • Division of a Line in Ratio (in tables) • Perpendicular Distance from a Point to a Line (in tables) • Translations, Symmetry • • • • Centroid Circumcentre Orthocentre Incentre • Real World Applications • • • • • • • • • • Standard Equation of a Circle (in tables) General Equation of a Circle (in tables) Touching Circles (Internally and Externally) Intersection of Line and a Circle Common Chord of a Circle Circle intersecting x and y axis Tangent to a Circle at a Point on the Circle Tangents to a Circle Parallel to a Given Line Tangent to a Circle at a Point NOT on the Circle Equation of a Circle Given: • 3 Points on the Circle • 2 Points and a Tangent to the Circle at a Given Point • 2 Points and the Equation of the Line containing the centre • 1 point, the length of the radius and the line containing the centre and the radius. Paper 2 Things to Learn Off Things to Learn Off Topics Solving Triangles (Small number of Tools) 8 Trigonometric Proofs Pythagoras ๐ 2 = ๐2 + ๐ 2 • cos2 ๐ด + sin2 ๐ด = 1 • Radian Measure • • Special Angles Cosine Rule ๐2 = ๐ 2 + ๐ 2 − 2๐๐ cos ๐ด • • • • • ๐ ๐ ๐ = = sin ๐ด sin ๐ต sin ๐ถ ๐2 = ๐ 2 + ๐ 2 − 2๐๐ cos ๐ด • Trigonometric Ratios (in tables) • Pythagoras Theorem (in tables) • Area of a Triangle (in tables) • Length of an Arc (in tables) • Area of a Sector (in tables) • 3D Problems • Graphing Trigonometric Functions • 8 Trigonometric Proofs (see left) • Application of the 24 Trigonometric Identities • Compound Angles • Double and Half Angles • Sum, Difference and Product • Solving Trigonometric Equations (see left) • Inverse Trigonometric Functions Trigonometry – Big topic that goes beyond just solving triangles. Algebra needs to be good and there is lots to learn off by heart. Needed for Complex numbers, the Line and Circle, Calculus and some Area and Volume questions! Sine Rule ๐ ๐ = sin ๐ด sin ๐ต • Area of Triangle 1 ๐๐ sin ๐ถ 2 cos ๐ด − ๐ต = cos ๐ด cos ๐ต + sin ๐ด sin ๐ต cos ๐ด + ๐ต = cos ๐ด cos ๐ต − sin ๐ด sin ๐ต cos 2๐ด = cos2 ๐ด − sin2 ๐ด sin ๐ด + ๐ต = sin ๐ด cos ๐ต + cos ๐ด sin ๐ต tan ๐ด + ๐ต = tan ๐ด+tan ๐ต 1−tan ๐ด tan ๐ต Signs of ratios (CAST) to find all solutions to Trigonometric Equations Tan, Sin or Cos ๐ ๐ ๐ด ๐= ๐= ๐ถ= ๐ด ๐ป ๐ป Radians Degrees Length of Arc ๐๐ 2๐๐ × Area of Sector 1 ๐๐ 2 2 ๐2 × ๐ 360 ๐ 360 ๐ Degrees to radians × 180 180 Radians to degrees × ๐ Enlargements – Small section with some construction or use of basic formula involved. The scale factor, k, is the number by which the object is enlarged. ๐๐๐๐ฅ๐ ๐ ๐๐๐ญ๐จ๐ซ ๐ = Image Length Object Length ๐๐ฆ๐๐ ๐ ๐๐ซ๐๐ = ๐ 2 × Object Area ๐๐ฆ๐๐ ๐ ๐๐จ๐ฅ๐ฎ๐ฆ๐ = ๐ 3 × Object Volume The centre of enlargement is the point from which the enlargement is constructed. A translation is when a point or shape is moved in a straight line. If we are given the object and the image we can find the center of enlargement by drawing lines through the corresponding vertices of the object and image. Central Symmetry is a reflection through a point An axial symmetry is a reflection in a line or axis. Paper 2 Things to Learn Off Things to Learn Off Geometry – A theorem is a statement deduced from the axioms by logical argument. A proof is a series of logical steps which we use to prove a theorem. The section that can get you the most ‘easy’ marks through learned constructions, theorems and definitions. A good knowledge of Geometry is needed to solve Trigonometry problems and can help in the Line and Circle sections. Theorem 11 If three parallel lines cut off equal segments on some transversal line, then they will cut off equal segments on any other transversal. Theorem 12 Let โABC be a triangle. If a line l is parallel to BC and cuts [AB] in the ratio s:t, then it also cuts [AC] in the same ratio. Theorem 13 If two triangles โABC and โA' B' C' are similar, then their sides are proportional, in order. Understand all Theorems 1 to 21 (sketching them out helps) An axiom is a statement accepted without proof, as a basis for argument. Axiom 1 (Two Points Axiom). There is exactly one line through any two given points. The converse of a theorem is the reverse of a theorem. Example: In an isosceles triangles the angles opposite the equal sides are equal. Converse: If two angles are equal in a triangle then the triangle is isosceles. Converse is true. Implies is a term we use in a proof when we can write down a fact we have proved from our previous statements. The symbol for implies is ⇒ Is equivalent to means something has the same value or measure as, or corresponds to, something else. For example $3 is equivalent to €2. If and only if: I will give you €100 if and only if you eat this apple. This means that if you eat this apple I’ll give you €100 and if I have given you €100 you have eaten the apple. Proof by Contradiction is where we cannot directly prove a statement but we can prove that the opposite statement is false. A corollary is a statement that follows readily from a previous theorem. Often a corollary is a statement of a theorem in a more specific context. Corollary 1. A diagonal divides a parallelogram into two congruent triangles Constructions 1 – 22 Proving Triangles are Congruent SSS SAS ASA Proving Triangles are Similar/ Equiangular (Angles are the same) www.mathspoints.ie