Precalculus (6th Edition)

Published by Pearson
ISBN 10: 013421742X
ISBN 13: 978-0-13421-742-0

Chapter 8 - Application of Trigonometry - 8.1 The Law of Sines - 8.1 Exercises - Page 754: 23

Answer

$$A = {56^ \circ }00',\,\,\,\,AB = 361{\text{ft}},\,\,\,\,BC = 308{\text{ft}}$$

Work Step by Step

$$\eqalign{ & B = {20^ \circ }50',\,\,\,C = {103^ \circ }10'{\text{,}}\,\,\,AC = 132{\text{ft}} \cr & {\text{The side }}AC{\text{ is }}b = 132{\text{ft}} \cr & \cr & {\text{Find }}A \cr & A = {180^ \circ } - B - C \cr & A = {180^ \circ } - {20^ \circ }50' - {103^ \circ }10' \cr & A = {56^ \circ } \cr & \cr & {\text{Use the law of sines to find side }}a{\text{ or }}BC \cr & \frac{a}{{\sin A}} = \frac{b}{{\sin B}} \cr & a = \frac{{b\sin A}}{{\sin B}} \cr & a = \frac{{132\sin \left( {{{56}^ \circ }} \right)}}{{\sin \left( {{{20}^ \circ }50'} \right)}} \cr & {\text{Use a calculator}} \cr & a = 307.698{\text{ft}} \cr & BC = 308{\text{ft}} \cr & \cr & {\text{Use the law of sines to find side }}c{\text{ or }}AB \cr & \frac{c}{{\sin C}} = \frac{b}{{\sin B}} \cr & c = \frac{{b\sin C}}{{\sin B}} \cr & c = \frac{{132\sin \left( {{{103}^ \circ }10'} \right)}}{{\sin \left( {{{20}^ \circ }50'} \right)}} \cr & {\text{Use a calculator}} \cr & c = 361.3{\text{ft}} \cr & AB = 361{\text{ft}} \cr & \cr & {\text{Answer}} \cr & A = {56^ \circ }00',\,\,\,\,AB = 361{\text{ft}},\,\,\,\,BC = 308{\text{ft}} \cr} $$
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