Chapter 8 - Polar Coordinates; Vectors - Section 8.2 Polar Equations and Graphs - 8.2 Assess Your Understanding - Page 606: 18

$x=4$ a vertical line 4 units right of the pole. See graph.

1. Use the formula $r\ cos\theta=x$, we have $r\ cos\theta=4\rightarrow x=4$ 2. We can identify the above equation as a vertical line 4 units right of the pole. 3. See graph.