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 9.1 Basic Functions 9.2 Solving Right Triangles 9.3 Trigonometric Identities 9.4 Graphing Trigonometric Functions 9.5 The Unit Circle

 9.6 Radians and Degrees 9.7 Graphing in the Entire Coordinate Plane 9.8 Key Formulas 9.9 Review Questions 9.10 Explanations
Trigonometric Identities
A trigonometric identity is an equation involving trigonometric functions that holds true for all angles. These identities are commonly called Pythagorean identities, because they come from the Pythagorean theorem.
1. tan = sin / cos
2. sin2+ cos2= 1
The Math IC will test your knowledge of the trigonometric identities by asking you to simplify a complex expression. Answering these questions has more to do with memorizing the identities and being good with algebraic substitution than it does with the theoretical concepts of trigonometry. For example:
 What is (costan ) / (sin – cos2)?
To solve a problem like this, use the trigonometric identities to simplify the trigonometric into sines and cosines. After you have simplified the expression using the identities, it is quite likely that the expressions will simplify further due to the canceling of terms. The simplification of the expression in the example question proceeds as follows:
Simplifying the mess given to you by the problem, you get sin2.
Here’s another example:
 What is tan2 cos2 + 1 – sin2?
 Jump to a New ChapterIntroduction to the SAT IIIntroduction to SAT II Math ICStrategies for SAT II Math ICMath IC FundamentalsAlgebraPlane GeometrySolid GeometryCoordinate GeometryTrigonometryFunctionsStatisticsMiscellaneous MathPractice Tests Are Your Best Friends
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