---
tag: 02E9VT1RVQ
kind: concept
name: Power of a point
msc: [51M04]
sources:
  - url: https://en.wikipedia.org/wiki/Power_of_a_point
    locator: lead section
same_as:
  wikidata: Q898575
  wikipedia: Power of a point
---

## Summary

The power of a point with respect to a circle is the square of its distance to the centre minus the square of the radius. It is positive outside the circle, zero on the circle and negative inside.