Abstract
We provide a visual proof that the infinite sum of the reciprocals of the triangular numbers is 1. Such visual proofs usually stack line segments or rectangular blocks. Here we stack angles.
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Paul Stephenson
Paul Stephenson taught mathematics and physics for two decades before creating a touring math lab structured around the multiple embodiment principle of the late Z. P. Dienes. The Magic Mathworks Traveling Circus, registered in the U. K. as a not-for-profit company, has now been on the road for thirty years.