Drag A,B, C to change the original triangle. Press Play to watch a spring driven equilateral triangle gradually settle at the maximum perimeter position.
Press Show to see the perpendiculars to the sides of the equilateral triangle through A, B and C.
Note that the mechanism settles at a position where these perpendiculars are concurrent.
This is a problem from The Mathematical Gazette March 2014 pp 79-84.

**Tags: Fermat, toricelli, equilateral, triangle**