Calculus 8th Edition

Published by Cengage
ISBN 10: 1285740629
ISBN 13: 978-1-28574-062-1

Chapter 15 - Multiple Integrals - 15.3 Double Integrals in Polar Coordinates - 15.3 Exercises - Page 1055: 17

Answer

$A$ = $\frac{\sqrt 3}{2}+\frac{\pi}{3}$

Work Step by Step

$A$ = $\int_{-\frac{\pi}{3}}^{\frac{\pi}{3}}\int_1^{2\cosθ}rdrdθ$ $A$ = $2\int_{0}^{\frac{\pi}{3}}\int_1^{2\cosθ}rdrdθ$ $A$ = $\int_{0}^{\frac{\pi}{3}}[r^2]_1^{2\cosθ}dθ$ $A$ = $\int_{0}^{\frac{\pi}{3}}[4\cos^2{θ}-1]dθ$ $A$ = $\int_{0}^{\frac{\pi}{3}}[2\cos2θ+1]dθ$ $A$ = $[\sin2θ+θ]_{0}^{\frac{\pi}{3}}$ $A$ = $\sin{\frac{2\pi}{3}}+\frac{\pi}{3}$ $A$ = $\frac{\sqrt 3}{2}+\frac{\pi}{3}$
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