Calculus: Early Transcendentals 9th Edition

Published by Cengage Learning
ISBN 10: 1337613924
ISBN 13: 978-1-33761-392-7

Chapter 7 - Section 7.1 - Integration by Parts - 7.1 Exercises - Page 491: 65

Answer

$A \approx 4$

Work Step by Step

$$\eqalign{ & {\text{Let }}y = \arcsin \left( {\frac{1}{2}x} \right){\text{ and }}y = 2 - {x^2} \cr & {\text{From the graph we have the intersection points}} \cr & x \approx - 1.75{\text{ and }}x = 1.17 \cr & {\text{The area of the region bounded by the curves is given by:}} \cr & A = \int_{ - 1.75}^{1.17} {\left[ {\left( {2 - {x^2}} \right) - \arcsin \left( {\frac{1}{2}x} \right)} \right]} dx \cr & \cr & {\text{* Integrating }}\int {\arcsin \left( {\frac{1}{2}x} \right)} dx \cr & u = \arcsin \left( {\frac{1}{2}x} \right),{\text{ }}du = \frac{1}{{\sqrt {4 - {x^2}} }}dx \cr & dv = dx,{\text{ }}v = x \cr & = x\arcsin \left( {\frac{1}{2}x} \right) - \int {\frac{x}{{\sqrt {4 - {x^2}} }}} dx \cr & = x\arcsin \left( {\frac{1}{2}x} \right) + \sqrt {4 - {x^2}} + C \cr & \cr & {\text{Therefore}}{\text{,}} \cr & \underbrace {A = \int_{ - 1.75}^{1.17} {\left[ {\left( {2 - {x^2}} \right) - \arcsin \left( {\frac{1}{2}x} \right)} \right]} dx}_ \Downarrow \cr & A = \left[ {2x - \frac{1}{3}{x^3} - x\arcsin \left( {\frac{1}{2}x} \right) - \sqrt {4 - {x^2}} } \right]_{ - 1.75}^{1.17} \cr & {\text{Evaluating}} \cr & A = \left[ {2.34 - \frac{1}{3}{{\left( {1.17} \right)}^3} - \left( {1.17} \right)\arcsin \left( {\frac{1}{2}\left( {1.17} \right)} \right) - \sqrt {4 - {{\left( {1.17} \right)}^2}} } \right] \cr & - \left[ { - 3.5 - \frac{1}{3}{{\left( { - 1.75} \right)}^3} - \left( {-1.75} \right)\arcsin \left( {\frac{1}{2}\left( {-1.75} \right)} \right) - \sqrt {4 - {{\left( {-1.75} \right)}^2}} } \right] \cr & {\text{Simplifying}} \cr & A \approx - 0.547 - \left( {4.546} \right) \cr & A \approx 4 \cr} $$
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