Pythagorean Theorem proof by Intersecting Chords Theorem

Pythagorean Theorem proof by Intersecting Chords Theorem The Intersecting Chords Theorem states that if any two chords intersect in a circle, then the products of their segments are equal. In our case, then FC ∙ CG = EC ∙ CD. In terms of a, b, and c: b ∙ b = (c - a)(c + a); using a little algebra, b² = c² - a²; rewriting, we have the familiar a² + b² = c² Pythagorean Theorem relationship in a right triangle. credits: http://peterashmathedblog.blogspot.com/2011/09/mathematics-and-humor.html http://www.cut-the-knot.org/proofs/IntersectingChordsTheorem.shtml