In any right triangle, (Hypotenuse)² = (one leg)² + (other leg)² . In an isosceles right triangle, the legs have equal lengths, so (Hypotenuse)² = (leg)² + (leg)² . (Hypotenuse)² = 2 (leg)² . Hypotenuse = √(2 leg²) Hypotenuse = leg √2 . In this particular isosceles right triangle, Hypotenuse = 6 √2 cm. leg √2 = 6 √2 leg = 6 cm