1. The problem statement, all variables and given/known data Prove that any chord perpendicular to the diameter of a circle is bisected by the diameter. 2. Relevant equations 3. The attempt at a solution I was thinking that maybe I could form two triangles, show that these triangles are congruent, and then conclude that the two lengths of the chord cut by the diameter are equal in length. But I can't seem to prove congruence.