The center is (2,-3)
radius is equal to sqrt(80)
Well the general equation of a circle is
Where r is the radius
h,y are real numbers, (x,y determines the center of the circle, notice that x,y in order to be the center of the circle have to make x-h=0 and y-k=0
so for example in your question,
notice h and k are -2,+3
solve it by the following
x=2 (First coordinate of the center) x coordinate
y=-3 (Second coordinate of the center) y coordinate
As the general equation of the circle says all of this should give you the radius squared.
So to find the radius we take the squareroot of the number simply
in your question
r=sqrt(80) Notice it can't be negative as it is a radius!