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 68

Find all values of θ, if θ is in the interval [0°, 360°) and has the given function value. See Example 6. √3 sin θ = - —— 2

검증된 단계별 안내
1
Recognize that the equation is \( \sin \theta = -\frac{\sqrt{3}}{2} \). We need to find all angles \( \theta \) in the interval \( [0^\circ, 360^\circ) \) where the sine value equals \( -\frac{\sqrt{3}}{2} \).
Recall the reference angle where \( \sin \theta = \frac{\sqrt{3}}{2} \) is \( 60^\circ \) because \( \sin 60^\circ = \frac{\sqrt{3}}{2} \). Since our sine value is negative, \( \theta \) must be in the quadrants where sine is negative.
Identify the quadrants where sine is negative: the third and fourth quadrants. So, the angles we seek are related to the reference angle \( 60^\circ \) but located in these quadrants.
Calculate the angles in the third and fourth quadrants by adding the reference angle to 180° and subtracting it from 360°, respectively. That is, \( \theta = 180^\circ + 60^\circ \) and \( \theta = 360^\circ - 60^\circ \).
Write the general solutions for \( \theta \) in the interval \( [0^\circ, 360^\circ) \) as \( \theta = 240^\circ \) and \( \theta = 300^\circ \).

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.

Unit Circle and Angle Measurement

The unit circle is a circle with radius 1 centered at the origin, used to define trigonometric functions for all angles. Angles are measured in degrees or radians, and the sine of an angle corresponds to the y-coordinate of the point on the unit circle. Understanding the interval [0°, 360°) means considering one full rotation around the circle.
추천 영상:
06:11
Introduction to the Unit Circle

Sine Function and Its Values

The sine function gives the ratio of the opposite side to the hypotenuse in a right triangle, or the y-coordinate on the unit circle. Knowing that sin θ = -√3/2 indicates the angle's sine value is negative, which occurs in the third and fourth quadrants where y-values are negative.
추천 영상:
5:08
Sine, Cosine, & Tangent of 30°, 45°, & 60°

Reference Angles and Quadrants

Reference angles are acute angles used to find sine values for angles in different quadrants. Since sine is negative in the third and fourth quadrants, you find the reference angle with positive sine √3/2 (which is 60°), then determine θ by adjusting for the correct quadrant within [0°, 360°).
추천 영상:
5:31
Reference Angles on the Unit Circle