Chapter 10 - Practice Exercises - Page 593: 29

Circle with center $(0,-2)$ and radius $2$

Here, we have $r=-4\sin \theta$ This implies that $r^2=-4r \sin \theta$ $x^2+y^2+4y=0$ or, $x^2+(y+4)^2=16$ Thus, we have an equation of a circle with center $(0,-2)$ and radius $2$