The name given to a

right isosceles triangle. So called because its angles measure 45°, 45°, and 90°. Notable because if one leg measures

*x*, then the

hypotenuse measures sqrt(2)

*x*. Proof:

- a²+b² = c²
*x*²+*x*² = c²- 2
*x*² = c² - c = sqrt(2
*x*²) - c = sqrt(2)
*x*.

Q.E.D.