enter image description hereThis might be trivial but integration by parts has a nice proof without words:

Pythagoras proof from circle. Inscribed triangle formed by semicircle is a right triangle. Similar triangles are formed having angles which are complementary.

the fundamental theorem of calculus

Math and Things : Photo

the fundamental theorem of calculus now available on a shirt @ cafepress.ca

Proofs without words: two algebraic identities about series. These are very beautiful with beads or other pretty counters. #MathWithoutWords

A useful way to remember sin(30), sin(45), sin(60): think "1, 2, 3"; cos(30), cos(45), cos(60): think "3, 2, 1" | www.mathisfun.com

Visual Log LawsBy Brittany Bordewyk, as a great response to Prof. Wilson’s visual exponent laws. Did I somehow never post these?