Answer
$(x+5)^2+y^2=25$, see graph.
Work Step by Step
Step 1. Multiply $r$ on both sides of the equation; we have $r^2=-10r\ cos\theta$
Step 2. Using $r^2=x^2+y^2$ and $x=r\ cos\theta$, we have $x^2+y^2=-10x$ or $x^2+10x+y^2=0$
Step 3. For a perfect square, we have $(x+5)^2+y^2=25$ which represents a circle with center $(-5,0)$ and radius of $5$
Step 4. We can graph the function as shown in the figure.
