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Ch. 5 - Trigonometric Identities
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161, 9780135440780, 9780136881117, 9780135440827, 9780135924891당신이 사용하는 게 아니라요?교과서 변경
6장, 문제 44

Write each function as an expression involving functions of θ or x alone. See Example 2.
tan(180° + θ)

검증된 단계별 안내
1
Recall the angle addition formula for tangent: \(\tan(a + b) = \frac{\tan a + \tan b}{1 - \tan a \tan b}\).
Identify the angles in the expression: here, \(a = 180^\circ\) and \(b = \theta\).
Use the fact that \(\tan 180^\circ = 0\) because tangent is zero at \(180^\circ\).
Substitute into the formula: \(\tan(180^\circ + \theta) = \frac{\tan 180^\circ + \tan \theta}{1 - \tan 180^\circ \tan \theta} = \frac{0 + \tan \theta}{1 - 0 \cdot \tan \theta} = \tan \theta\).
Consider the sign of the tangent function in the third quadrant (where \(180^\circ + \theta\) lies) to determine the correct expression for \(\tan(180^\circ + \theta)\) in terms of \(\tan \theta\).

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.

주요 개념

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

Angle Addition Formula for Tangent

The angle addition formula for tangent states that tan(a + b) = (tan a + tan b) / (1 - tan a tan b). This formula allows us to express the tangent of a sum of two angles in terms of the tangents of the individual angles, which is essential for rewriting tan(180° + θ).
추천 영상:
가이드 코스
3:17
Inverse Tangent

Tangent Function Periodicity

The tangent function has a period of 180°, meaning tan(θ + 180°) = tan θ. This property simplifies expressions involving angles shifted by 180°, allowing us to rewrite tan(180° + θ) directly as tan θ.
추천 영상:
가이드 코스
5:43
Introduction to Tangent Graph

Reference Angles and Quadrant Sign Rules

Understanding the signs of trigonometric functions in different quadrants helps determine the correct value of tan(180° + θ). Since 180° + θ lies in the third quadrant where tangent is positive, this confirms the sign of the expression after simplification.
추천 영상:
가이드 코스
5:31
Reference Angles on the Unit Circle