Answer
Center: $(1,-2)$
Radius: $4$
See graph
Work Step by Step
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:
