# The power of a point relative to a circle: powerpc

### 13.11.7 The power of a point relative to a circle: powerpc

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.

Input:

powerpc(circle(0, 1+i), 3+i)

Output:

8