Answer
A vertical line 3 units to the left of the y-axis.
Work Step by Step
Conversion of polar coordinates and Cartesian coordinates are as follows:
a)$r^2=x^2+y^2 \implies r=\sqrt {x^2+y^2}$
b) $\tan \theta =\dfrac{y}{x} \implies \theta =\tan^{-1} (\dfrac{y}{x})$
c) $x=r \cos \theta$ d) $y=r \sin \theta$
As we know that $\sec \theta=\dfrac{1}{\cos \theta}$
Therefore, $r \cos \theta =-3 \implies x=-3$
This shows a vertical line 3 units to the left of the y-axis.