In the case of the HL Congruence rule the hypotenuse and leg are the elements used to test for congruence. The ratio between the sides of this triangle is 11Sqrt2 which means that the length of the legs are equal and the length of the hypotenuse is simply the leg length multiplied by the square root of two. The hypotenuse formula which you may already know is the formal mathematical expression of the Pythagorean theorem.
Diagram 1 Diagram 2.
Here a b are opposite and adjacent sides respectively. Length of Hypotenuse² Length of side 1² Length of side 2². If FB DB BA BC FB AE and DB CE show that AE CE. The hypotenuse formula which you may already know is the formal mathematical expression of the Pythagorean theorem.