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: 30

Answer

$$B = {67^ \circ }45',\,\,\,\,\,\,a = 22.03{\text{mm}},\,\,\,\,\,\,\,b = 37.5{\text{mm}}$$

Work Step by Step

$$\eqalign{ & C = {79^ \circ }18',\,\,\,c = 39.81{\text{mm,}}\,\,\,A = {32^ \circ }57' \cr & \cr & {\text{Find }}B \cr & B = {180^ \circ } - A - C \cr & B = {180^ \circ } - {32^ \circ }57' - {79^ \circ }18' \cr & B = {67^ \circ }45' \cr & \cr & {\text{Use the law of sines to find side }}a \cr & \frac{a}{{\sin A}} = \frac{c}{{\sin C}} \cr & a = \frac{{c\sin A}}{{\sin C}} \cr & a = \frac{{39.81\sin \left( {{{32}^ \circ }57'} \right)}}{{\sin \left( {{{79}^ \circ }18'} \right)}} \cr & {\text{Use a calculator}} \cr & a = 22.03{\text{mm}} \cr & \cr & {\text{Use the law of sines to find side }}b \cr & \frac{b}{{\sin B}} = \frac{c}{{\sin C}} \cr & b = \frac{{c\sin B}}{{\sin C}} \cr & b = \frac{{39.81\sin \left( {{{67}^ \circ }45'} \right)}}{{\sin \left( {{{79}^ \circ }18'} \right)}} \cr & {\text{Use a calculator}} \cr & b = 37.5{\text{mm}} \cr & \cr & {\text{Answer}} \cr & B = {67^ \circ }45',\,\,\,\,\,\,a = 22.03{\text{mm}},\,\,\,\,\,\,\,b = 37.5{\text{mm}} \cr} $$
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