Precalculus (6th Edition) Blitzer

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

Chapter 6 - Section 6.1 - The Law of Sines - Exercise Set - Page 720: 3

Answer

The required values are $A=44{}^\circ,b\approx 18.6$, and $c\approx 22.8$.

Work Step by Step

At first we will find A. Property of a triangle: Sum of three angles is $A+B+C=180{}^\circ $ $\begin{align} & A+B+C=180{}^\circ \\ & A+54{}^\circ +82{}^\circ =180{}^\circ \\ & A=180{}^\circ -136{}^\circ \\ & A=44{}^\circ \end{align}$ Now, to find the remaining sides we will use the ratio $\frac{a}{\sin A}$ or $\frac{16}{\sin 44{}^\circ }$, Now, we will use the law of sines to find b. $\begin{align} & \frac{b}{\sin B}=\frac{a}{\sin A} \\ & \frac{b}{\sin 54{}^\circ }=\frac{16}{\sin 44{}^\circ } \\ & b=\frac{16\sin 54{}^\circ }{\sin 44{}^\circ } \\ & b=18.6 \end{align}$. Again use the law of sines to find c $\begin{align} & \frac{c}{\sin C}=\frac{a}{\sin A} \\ & \frac{c}{\sin 82{}^\circ }=\frac{16}{\sin 44{}^\circ } \\ & c=\frac{16\sin 82{}^\circ }{\sin 44{}^\circ } \\ & c=22.8 \end{align}$ The solution is $A=44{}^\circ,b\approx 18.6$, and $c\approx 22.8$.
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