26.10.7  Power of a point relative to a circle

Given a circle C of radius r and a point A at a distance of d from the center of C, the power of A relative to C is d² − r².

The powerpc command finds the power of a point relative to a circle.

• powerpc takes two arguments:
  • C, a circle.
  • P, a point.
• powerpc(C,P) returns the power of P relative to C.

Example