Precalculus (6th Edition) Blitzer

Published by Pearson
ISBN 10: 0-13446-914-3
ISBN 13: 978-0-13446-914-0

Chapter 6 - Mid-Chapter Check Point - Page 756: 2

Answer

There is one triangle and the solution is $C=101{}^\circ,B=37{}^\circ,c=92.4$

Work Step by Step

The provided angles and sides of the triangle are provided below: $A=42{}^\circ,a=63,b=57$ Using the law of sine we will find the angle B of the triangle. That is, $\begin{align} & \frac{\sin A}{a}=\frac{\sin B}{b} \\ & \frac{\sin 42{}^\circ }{63}=\frac{\operatorname{sinB}}{57} \\ & \operatorname{sinB}=57\times \frac{\sin 42{}^\circ }{63} \\ & =0.6054 \end{align}$ For this there are two angles possible, that is, $\begin{align} & {{B}_{1}}=37{}^\circ \\ & {{B}_{2}}=180{}^\circ -37{}^\circ \\ & =143{}^\circ \end{align}$ But ${{B}_{2}}$ is nota possible angle because $42{}^\circ +143{}^\circ =185{}^\circ $. Therefore, the possible angle is ${{B}_{1}}$ The angle C will be determined as below: $\begin{align} & C=180-{{B}_{1}}-A \\ & =180{}^\circ -37{}^\circ -42{}^\circ \\ & =101{}^\circ \end{align}$ Using the law of sines we will find c, that is: $\begin{align} & \frac{c}{\sin C}=\frac{a}{\operatorname{sinA}} \\ & \frac{c}{\sin 101{}^\circ }=\frac{63}{\sin 42{}^\circ } \\ & c=\sin 101{}^\circ \times \frac{63}{\sin 42{}^\circ } \\ & =92.4 \end{align}$ As the values of the measurements of the triangle are unique, therefore, there is one triangle and the measurement of the triangle are: ${{B}_{1}}\left( B \right)=37{}^\circ,C=101{}^\circ,\ \text{ and }\ c=92.4$
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