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: 25

Answer

$$B = {109.95^ \circ },\,\,\,a = 27{\text{m}},\,\,\,\,c = 21.4{\text{m}}$$

Work Step by Step

$$\eqalign{ & A = {39.70^ \circ },\,\,\,C = {30.35^ \circ }{\text{,}}\,\,\,b = 39.74{\text{m}} \cr & \cr & {\text{Find }}B \cr & B = {180^ \circ } - A - C \cr & B = {180^ \circ } - {39.70^ \circ } - {30.35^ \circ } \cr & B = {109.95^ \circ } \cr & \cr & {\text{Use the law of sines to find side }}a \cr & \frac{a}{{\sin A}} = \frac{b}{{\sin B}} \cr & a = \frac{{b\sin A}}{{\sin B}} \cr & a = \frac{{39.74\sin \left( {{{39.70}^ \circ }} \right)}}{{\sin \left( {{{109.95}^ \circ }} \right)}} \cr & {\text{Use a calculator}} \cr & a = 27{\text{m}} \cr & \cr & {\text{Use the law of sines to find side }}c \cr & \frac{c}{{\sin C}} = \frac{b}{{\sin B}} \cr & c = \frac{{b\sin C}}{{\sin B}} \cr & c = \frac{{39.74\sin \left( {{{30.35}^ \circ }} \right)}}{{\sin \left( {{{109.95}^ \circ }} \right)}} \cr & {\text{Use a calculator}} \cr & c = 21.4{\text{m}} \cr & \cr & {\text{Answer}} \cr & B = {109.95^ \circ },\,\,\,a = 27{\text{m}},\,\,\,\,c = 21.4{\text{m}} \cr} $$
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