## Precalculus (10th Edition)

Center: $(1,-2)$ Radius: $4$ See graph
We are given the circle: $x^2+y^2-2x+4y-11=0$ Put the equation in standard form: $(x-h)^2+(y-k)^2=r^2$ $(x^2-2x+1)-1+(y^2+4y+4)-4-11=0$ $(x-1)^2+(y+2)^2=16$ Identify $h,k,r$: $h=1$ $k=-2$ $r=\sqrt{16}=4$ The circle has center $(1,-2)$ and radius 4. Graph the circle: