Chapter 78, Problem 17A

In each of the following exercises, three views of a part are shown. The angular surfaces are to be machined in reference to the horizontal plane at $\angle A$ and $\angle B$ as shown in the front and right side views. Compute the required angles using these formulas:

$\tan \angle R=\frac{\tan \angle A}{\tan \angle B}$

$\cot \angle C=\sqrt{{\cot }^2\angle A+{\cot }^2\angle B}$

Given: $\angle A=31.60°$

$\angle C=28.00°$

a. Compute $\angle B.$
b. Compute $\angle R$ .

Use this figure for Exercises 15, 16, and 17.