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Ch. 1 - Trigonometric Functions
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161당신이 사용하는 게 아니라요?교과서 변경
2장, 문제 16

Use the appropriate reciprocal identity to find each function value. Rationalize denominators when applicable. See Example 1. cot θ , given that tan θ = 18

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1
Recall the reciprocal identity that relates cotangent and tangent: \(\cot \theta = \frac{1}{\tan \theta}\).
Substitute the given value of \(\tan \theta = 18\) into the identity: \(\cot \theta = \frac{1}{18}\).
Since the denominator is a whole number, check if rationalization is needed. In this case, the denominator is already rational, so no further rationalization is necessary.
Express the final answer as a simplified fraction or decimal, depending on the preferred form.
Review the result to ensure it aligns with the reciprocal identity and the given value.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Reciprocal Identities

Reciprocal identities relate pairs of trigonometric functions such as tangent and cotangent, where cot θ is the reciprocal of tan θ. This means cot θ = 1 / tan θ, allowing you to find one function value if the other is known.
추천 영상:
6:25
Pythagorean Identities

Rationalizing the Denominator

Rationalizing the denominator involves eliminating any irrational numbers (like square roots) from the denominator of a fraction. This is done by multiplying numerator and denominator by a suitable expression to simplify the expression and present it in a standard form.
추천 영상:
2:58
Rationalizing Denominators

Evaluating Trigonometric Functions from Given Values

When given the value of one trigonometric function, you can use identities and algebraic manipulation to find related functions. Here, knowing tan θ allows direct calculation of cot θ using reciprocal identities, ensuring correct substitution and simplification.
추천 영상:
7:28
Evaluate Composite Functions - Values Not on Unit Circle