A circle in the xy-plane has the equation (x-13)2+(y-k)2=64. Which of the following gives the center of the circle and its radius?
The center is at (13,k) and the radius is 8 .
The center is at (k,13) and the radius is 8 .
The center is at (k,13) and the radius is 64 .
The center is at (13,k) and the radius is 64 .