## Trigonometry (11th Edition) Clone

Published by Pearson

# Chapter 6 - Inverse Circular Functions and Trigonometric Equations - Section 6.2 Trigonometric Equations I - 6.2 Exercises - Page 274: 67c

#### Answer

$$t\approx0.21$$

#### Work Step by Step

$$V=\cos2\pi t$$ where $t\in[0,\frac{1}{2}]$ As $V=0.25$, we would have the equation: $$\cos2\pi t=0.25=\frac{1}{4}$$ So, $$2\pi t=\cos^{-1}\frac{1}{4}\approx1.318 (rad)$$ (be careful about radians and degrees) $$t=\frac{1.318}{2\pi}$$ $$t\approx0.21$$ $t\approx0.21$ is the result of this question.

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