Answer
A vertical line 3 units to the left of the y-axis.
Work Step by Step
The conversion of polar coordinates and Cartesian coordinates are described as follows:
1. $r^2=x^2+y^2$ and $r=\sqrt {x^2+y^2}$
2. $\tan \theta =\dfrac{y}{x} \implies \theta =\tan^{-1} (\dfrac{y}{x})$
3. $x=r \cos \theta$ and 4. $y=r \sin \theta$
Given: $\sec \theta=\dfrac{1}{\cos \theta}$
This implies that $r \cos \theta =-3$ and $x=-3$
Thus, this shows a vertical line 3 units to the left of the $y$-axis.
