Chapter 9.3, Problem 18E

Solution

To sketch: the given angle and to find its reference angle.

  

The reference angle is ${\theta }^{\prime }={40}^{\circ }$ .

Given:

  ${320}^{\circ }$ .

Calculation:

Let $\theta ={320}^{\circ }$ .

Now the sketch of the given angle is,

  

Here, the terminal side of $\theta$ lies in Quadrant IV.

So, the reference angle is

  $\begin{array}{c}{\theta }^{\prime }={360}^{\circ }-{320}^{\circ }\\ ={40}^{\circ }\end{array}$