Acircle is centered at the point (-7, -1) and passes through the point (8, 7).
the radius of the circle is units. the point (-15, lies on this circle.

The equation of the circle is

for some radius .

We find by plugging in the point :






So the radius is 17, and the equation is


For the second part of the question, we plug in :







So the answer could either be 14 or -16.

The answer would be a