40-50-90 Triangle
Definition: A triangle in which both legs are congruent, and the length of the hypotenuse is the length of a leg times the square root of 2.
Symbol/Notation: none
Statement: The triangle shown above is a 40-50-90 triangle because the length of its hypotenuse is equal to the sqrt(2) times the length of one of its legs, which is 3.