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Ch. 5 - Trigonometric Identities
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161당신이 사용하는 게 아니라요?교과서 변경
6장, 문제 5.1.48

Perform each transformation. See Example 2.
Write cot x in terms of sin x.

검증된 단계별 안내
1
Recall the definition of cotangent in terms of sine and cosine: \(\cot x = \frac{\cos x}{\sin x}\).
Since the problem asks to write \(\cot x\) in terms of \(\sin x\) only, we need to express \(\cos x\) in terms of \(\sin x\).
Use the Pythagorean identity: \(\sin^2 x + \cos^2 x = 1\), which can be rearranged to \(\cos x = \pm \sqrt{1 - \sin^2 x}\).
Substitute \(\cos x\) back into the cotangent expression: \(\cot x = \frac{\pm \sqrt{1 - \sin^2 x}}{\sin x}\).
Note that the sign depends on the quadrant where \(x\) lies, so the final expression for \(\cot x\) in terms of \(\sin x\) is \(\cot x = \pm \frac{\sqrt{1 - \sin^2 x}}{\sin x}\).

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주요 개념

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

Definition of Cotangent

Cotangent (cot x) is the reciprocal of the tangent function. It can be expressed as cot x = cos x / sin x, which relates cotangent directly to sine and cosine functions.
추천 영상:
5:37
Introduction to Cotangent Graph

Relationship Between Sine and Cosine

Sine and cosine are fundamental trigonometric functions related by the Pythagorean identity: sin²x + cos²x = 1. This identity allows expressing one function in terms of the other, which is useful when rewriting cotangent solely in terms of sine.
추천 영상:
5:05
Amplitude and Reflection of Sine and Cosine

Algebraic Manipulation of Trigonometric Expressions

Transforming trigonometric expressions often requires algebraic skills such as substitution and rearrangement. To write cot x in terms of sin x, one must manipulate the expression cot x = cos x / sin x using identities and algebraic steps.
추천 영상:
6:36
Simplifying Trig Expressions