# Tangents to an Excircle

Tangents to an Excircle

A circle drawn outside a triangle that is tangent to the extensions of two of its sides and to the third side is an excircle.

Let ABC be a triangle. Construct the excircle with center O opposite A. Let D and E be the points of intersection between the line perpendicular to AO and the extensions of AB and AC. Then .

DE=2

BD×CE