In Exercises 59–62, use a calculator to find the value of the acute angle θ in radians, rounded to three decimal places. cos θ = 0.4112
Ch. 1 - Angles and the Trigonometric Functions

1장, 문제 1.3.55
Find the reference angle for each angle.
23π/4
검증된 단계별 안내1
First, understand that the reference angle is the acute angle formed between the terminal side of the given angle and the x-axis. It is always between 0 and \( \frac{\pi}{2} \).
Since the given angle is \( \frac{23\pi}{4} \), which is greater than \( 2\pi \), we need to find its equivalent angle between 0 and \( 2\pi \) by subtracting multiples of \( 2\pi \).
Calculate the equivalent angle by subtracting \( 2\pi = \frac{8\pi}{4} \) repeatedly from \( \frac{23\pi}{4} \) until the result is between 0 and \( 2\pi \). This can be expressed as \( \frac{23\pi}{4} - n \times 2\pi \) where \( n \) is an integer.
Once you find the equivalent angle \( \theta \) in the interval \( [0, 2\pi) \), determine which quadrant \( \theta \) lies in to find the reference angle.
Use the quadrant information to calculate the reference angle \( \alpha \) as follows: if \( \theta \) is in Quadrant I, \( \alpha = \theta \); Quadrant II, \( \alpha = \pi - \theta \); Quadrant III, \( \alpha = \theta - \pi \); Quadrant IV, \( \alpha = 2\pi - \theta \).

비슷한 문제에 대한 검증된 영상 답변:
이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
영상 길이:
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주요 개념
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Reference Angle
A reference angle is the acute angle formed between the terminal side of a given angle and the x-axis. It is always positive and less than or equal to 90°, used to simplify trigonometric calculations by relating angles to their acute counterparts.
추천 영상:
Reference Angles on the Unit Circle
Angle Reduction Using Coterminal Angles
Coterminal angles differ by full rotations of 2π radians (360°). To find a reference angle for large angles like 23π/4, reduce the angle by subtracting multiples of 2π until it lies within one full rotation (0 to 2π).
추천 영상:
Coterminal Angles
Quadrant Identification
Determining the quadrant where the angle's terminal side lies is essential because the reference angle depends on the quadrant. Each quadrant has a specific way to calculate the reference angle based on the angle's position relative to the x-axis.
추천 영상:
Quadratic Formula
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