Number of Tangents from a Point

Core concept

This property of equal tangent lengths from an external point is proven using congruent triangles — the two triangles formed by the centre, the external point, and each point of tangency are congruent (by RHS criterion, since both share the hypotenuse to the external point, have equal radii, and both have a right angle at the point of tangency), directly proving the two tangent segments must be equal in length.