# Precalculus : Fundamental Trigonometric Identities

## Example Questions

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### Example Question #61 : Fundamental Trigonometric Identities Possible Answers:     Correct answer: Explanation:

Using these basic identities:   we find the original expression to be which simplifies to .

Further simplifying: The cosines cancel, giving us ### Example Question #62 : Fundamental Trigonometric Identities

Which of the following is the best answer for ?

Possible Answers:     Correct answer: Explanation:

Write the Pythagorean identity. Substract from both sides. The other answers are incorrect.

### Example Question #63 : Fundamental Trigonometric Identities

Express in terms of only sines and cosines.

Possible Answers:     Correct answer: Explanation:

The correct answer is . Begin by substituting  , and . This gives us: .

### Example Question #171 : Trigonometric Functions

Express in terms of only sines and cosines.

Possible Answers:     Correct answer: Explanation:

To solve this problem, use the identities   , and . Then we get   1 2 3 4 5 7 Next →

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