Question 143179
the center is the midpoint of the diameter __ [(6+20)/2,(9+7)/2] __ (13,8)


the radius is the distance from the mid-point to one end __ r^2=(20-13)^2+(7-8)^2 __ r^2=49+1 __ r^2=50


(x-13)^2+(y-8)^2=50