Tangent Length from an External Point

Tangent Length from an External Point

For a circle with centre $$c$$ and radius $$r$$, and external point $$p$$:

$$PT=\sqrt{PC^2-r^2}$$

Terminology

- $$PT$$ → Length of tangent from $$p$$ to the circle.

- $$PC$$ → Distance between the external point and centre.

Usage

- Used to calculate the length of either tangent drawn from an external point.