Trigonometry (11th Edition) Clone

Published by Pearson
ISBN 10: 978-0-13-421743-7
ISBN 13: 978-0-13421-743-7

Chapter 3 - Quiz (Sections 3.1-3.3) - Page 126: 7



Work Step by Step

RECALL: In a unit circle, $\cos{s} = x$ (Refer to Figure 13 on page 111) The angle $\frac{7\pi}{4}$ intersects the unit circle at the point $(\frac{\sqrt2}{2}, -\frac{\sqrt2}{2})$. This point has $x=\frac{\sqrt2}{2}$ and $y=-\frac{\sqrt2}{2}$. Since $\cos{s}=x$, then $\cos{\frac{7\pi}{4}} =\frac{\sqrt2}{2}$
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