Question

The equation of a circle is (x + 12)2 + (y + 16)2 = (r1)2, and the circle passes through the origin. The equation of the circle then changes to (x – 30)2 + (y – 16)2 = (r2)2, and the circle still passes through the origin. What are the values of r1 and r2?

Answer 1

The circle passes through the origin means the point (0,0) is on the circle.
Plug in (0,0) into each equation to find r.

Answer 2

the first set of equations or the second set?

Answer 3

It says they both pass through the origin.