Calculus: Early Transcendentals 9th Edition

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

APPENDIX D - Trigonometry - D Exercises - Page A 35: 81

Answer

$\text{Area}\approx14.34457\,cm^{2}$

Work Step by Step

Using the law of cosines, we have $(|CA|)^{2}=(|AB|)^{2}+(|BC|)^{2}-2(|AB|)(|BC|)\cos B$ $=(10\,cm)^{2}+(3\,cm)^{2}-2(10\,cm)(3\,cm)\cos 107^{\circ}$ $\approx126.542302\,cm^{2}$ $|CA|\approx11.2491023\,cm$ The semiperimeter of the triangle is $s=\frac{1}{2}(10\,cm+3\,cm+11.2491023\,cm)$ $=12.1245512\,cm$ $\text{Area}=\sqrt {s(s-a)(s-b)(s-c)}$ where $a,b $ and $c$ are the lengths of the sides of the triangle. $\text{Area}=\sqrt {12.1245512(2.1245512)(9.1245512)(0.8754489)}cm^{2}$ $\approx14.34457\,cm^{2}$
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