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: 4

Answer

The required values are $B=19{}^\circ,b\approx 9.6$, and $c\approx 23.1$.

Work Step by Step

At first we will find B. Property of a triangle: Sum of three angles is $A+B+C=180{}^\circ $ $\begin{align} & A+B+C=180{}^\circ \\ & 33{}^\circ +B+128{}^\circ =180{}^\circ \\ & B=180{}^\circ -161{}^\circ \\ & B=19{}^\circ \end{align}$ Now, to find the remaining sides, we will use the ratio $\frac{a}{\sin A}$ or $\frac{16}{\sin 33{}^\circ }$, Now, we will use the law of sines to find b. $\begin{align} & \frac{b}{\sin B}=\frac{a}{\sin A} \\ & \frac{b}{\sin 19{}^\circ }=\frac{16}{\sin 33{}^\circ } \\ & b=\frac{16\sin 19{}^\circ }{\sin 33{}^\circ } \\ & b=9.6 \end{align}$ Again use the law of sines to find c $\begin{align} & \frac{c}{\sin C}=\frac{a}{\sin A} \\ & \frac{c}{\sin 128{}^\circ }=\frac{16}{\sin 33{}^\circ } \\ & c=\frac{16\sin 128{}^\circ }{\sin 33{}^\circ } \\ & c=23.1 \end{align}$ The solution is $B=19{}^\circ,b\approx 9.6$, and $c\approx 23.1$.
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.