There is a special relationship among the measures of the sides of a 45°-45°-90° triangle.
45°-45°-90° triangle is commonly encountered right triangle whose sides are in the proportion . The measures of the sides are x , x , and .
In a 45°-45°-90° triangle, the length of the hypotenuse is times the length of a leg.
To see why this is so, note that by the Converse of the Pythagorean Theorem, these values make the triangle a right triangle.