Skip to main content
Ch. 2 - Acute Angles and Right Triangles
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161당신이 사용하는 게 아니라요?교과서 변경
3장, 문제 66

Find all values of θ, if θ is in the interval [0°, 360°) and has the given function value. See Example 6. √3 cot θ = - —— 3

검증된 단계별 안내
1
Start by writing down the given equation: \(\cot \theta = -\frac{\sqrt{3}}{3}\).
Recall that \(\cot \theta = \frac{1}{\tan \theta}\), so rewrite the equation as \(\frac{1}{\tan \theta} = -\frac{\sqrt{3}}{3}\), which implies \(\tan \theta = -\frac{3}{\sqrt{3}}\).
Simplify \(\tan \theta = -\frac{3}{\sqrt{3}}\) to get \(\tan \theta = -\sqrt{3}\).
Determine the reference angle where \(\tan \theta = \sqrt{3}\). From the unit circle or common angles, \(\tan 60^\circ = \sqrt{3}\), so the reference angle is \(60^\circ\).
Since \(\tan \theta\) is negative, find all angles in the interval \([0^\circ, 360^\circ)\) where tangent is negative. Tangent is negative in the second and fourth quadrants, so the solutions are \(\theta = 180^\circ - 60^\circ\) and \(\theta = 360^\circ - 60^\circ\).

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
영상 길이:
3m
도움이 되었나요?

주요 개념

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

Cotangent Function and Its Definition

Cotangent (cot θ) is the reciprocal of the tangent function, defined as cot θ = cos θ / sin θ. Understanding this relationship helps in converting cotangent values into sine and cosine ratios, which is essential for solving trigonometric equations.
추천 영상:
5:37
Introduction to Cotangent Graph

Solving Trigonometric Equations in a Given Interval

When solving for θ within [0°, 360°), it is important to find all angles that satisfy the equation. This involves considering the periodicity of trigonometric functions and identifying all solutions in the specified range, including those in different quadrants.
추천 영상:
4:34
How to Solve Linear Trigonometric Equations

Sign of Trigonometric Functions in Different Quadrants

The sign of cotangent depends on the signs of sine and cosine, which vary by quadrant. Cotangent is negative where sine and cosine have opposite signs, specifically in the second and fourth quadrants, guiding the selection of correct angle solutions.
추천 영상:
6:04
Introduction to Trigonometric Functions