Trigonometry (10th Edition)

Published by Pearson
ISBN 10: 0321671775
ISBN 13: 978-0-32167-177-6

Chapter 7 - Review Exercises - Page 343: 20

Answer

The angles of the triangle are as follows: $A = 47.7^{\circ}, B = 74.0^{\circ},$ and $C = 58.3^{\circ}$ The lengths of the sides are as follows: $a = 94.6~yd$, $b = 123~yd$, and $c = 109~yd$

Work Step by Step

$a = 94.6~yd$ $b = 123~yd$ $c = 109~yd$ We can use the law of cosines to find $B$: $b^2 = a^2+c^2-2ac~cos~B$ $2ac~cos~B = a^2+c^2-b^2$ $cos~B = \frac{a^2+c^2-b^2}{2ac}$ $B = arccos(\frac{a^2+c^2-b^2}{2ac})$ $B = arccos(\frac{94.6^2+109^2-123^2}{(2)( 94.6)( 109)})$ $B = arccos(0.27645)$ $B = 74.0^{\circ}$ We can use the law of sines to find the angle $A$: $\frac{b}{sin~B} = \frac{a}{sin~A}$ $sin~A = \frac{a~sin~B}{b}$ $sin~A = \frac{(94.6)~sin~(74.0^{\circ})}{123}$ $sin~A = 0.7393$ $A = arcsin(0.7393)$ $A = 47.7^{\circ}$ We can find angle $C$: $A+B+C = 180^{\circ}$ $C = 180^{\circ}-A-B$ $C = 180^{\circ}-47.7^{\circ}-74.0^{\circ}$ $C = 58.3^{\circ}$
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.