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Ch. 3 - Radian Measure and The Unit Circle
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161Not the one you use?Change textbook
Chapter 4, Problem 90

Give an expression that generates all angles coterminal with an angle of π/2 radians. Let n represent any integer.

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1
Recall that angles are coterminal if they differ by an integer multiple of a full rotation. In radians, a full rotation is \(2\pi\).
Given the angle \(\frac{\pi}{2}\), to find all angles coterminal with it, we add integer multiples of \(2\pi\) to this angle.
Express this mathematically as \(\theta = \frac{\pi}{2} + 2\pi n\), where \(n\) is any integer (positive, negative, or zero).
This expression generates all angles that share the same terminal side as \(\frac{\pi}{2}\) when drawn in standard position.
Thus, the general formula for all coterminal angles with \(\frac{\pi}{2}\) is \(\theta = \frac{\pi}{2} + 2\pi n\), with \(n \in \mathbb{Z}\).

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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. In radians, adding or subtracting multiples of 2π to an angle results in coterminal angles. This concept helps identify all angles equivalent in position on the unit circle.
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Coterminal Angles

Angle Measurement in Radians

Radians measure angles based on the radius of a circle, where 2π radians equal one full rotation (360 degrees). Understanding radians is essential for expressing angles and their coterminal counterparts in a mathematically consistent way.
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Converting between Degrees & Radians

General Expression for Coterminal Angles

The general formula for coterminal angles is θ + 2πn, where θ is the initial angle and n is any integer. This expression generates all angles coterminal with θ by adding full rotations, allowing for a complete set of equivalent angles.
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Coterminal Angles