In Exercises 55β58, use a calculator to find the value of the acute angle ΞΈ to the nearest degree. sin ΞΈ = 0.2974
Ch. 1 - Angles and the Trigonometric Functions

Chapter 1, Problem 1.1.68
In Exercises 57β70, find a positive angle less than or that is coterminal with the given angle. -π/40
Verified step by step guidance1
Understand that two angles are coterminal if they differ by an integer multiple of \(2\pi\). This means we can add or subtract \(2\pi\) to the given angle to find coterminal angles.
The given angle is \(-\frac{\pi}{40}\). Since it is negative, to find a positive coterminal angle less than or equal to \(2\pi\), add \(2\pi\) to it.
Write the expression for the coterminal angle: \(-\frac{\pi}{40} + 2\pi\).
To add these, express \(2\pi\) with a denominator of 40: \(2\pi = \frac{80\pi}{40}\). So the sum becomes \(-\frac{\pi}{40} + \frac{80\pi}{40} = \frac{79\pi}{40}\).
Verify that \(\frac{79\pi}{40}\) is positive and less than or equal to \(2\pi\) to confirm it is the desired coterminal angle.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Coterminal Angles
Coterminal angles are angles that share the same initial and terminal sides but differ by full rotations of 2Ο radians. To find a coterminal angle, you add or subtract multiples of 2Ο until the angle lies within the desired range, such as between 0 and 2Ο.
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Coterminal Angles
Angle Measurement in Radians
Angles can be measured in radians, where 2Ο radians equal 360 degrees. Understanding radian measure is essential for working with trigonometric functions and converting between degrees and radians when necessary.
Recommended video:
Converting between Degrees & Radians
Positive Angle Determination
Finding a positive angle less than or equal to 2Ο involves adjusting the given angle by adding 2Ο repeatedly if it is negative. This ensures the angle is expressed within the standard interval for trigonometric analysis.
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Drawing Angles in Standard Position
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