Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

Published by Pearson
ISBN 10: 0-32193-104-1
ISBN 13: 978-0-32193-104-7

Chapter 6 - Analytic Trigonometry - Section 6.6 Double-angle and Half-angle Formulas - 6.6 Assess Your Understanding - Page 521: 117

Answer

$\dfrac{\sqrt{3}+1}{2}$

Work Step by Step

$\sin \frac{2 \pi}{3}-\cos \frac{4 \pi}{3}$ $=\sin \frac{2 \times 180}{3}-\cos \frac{4 \times 180}{3}$ $=\sin 120-\cos 240^{\circ}$ $=\sin (180-60)^{\circ}-\cos (180+60)$ $=\sin 60^{\circ}-\left(-\cos 60^{\circ}\right)$ $=\dfrac{\sqrt{3}}{2}+\dfrac{1}{2}$ $=\dfrac{\sqrt{3}+1}{2}$
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