You can do the Pythagorean theorem, but plug in the hypotenuse first, and both of the values for the legs would be the same. 10^2 = 2(c^2) 100 = 2(c^2) 50 = c^2 c=√50 which is about 7.07
The sides opposite of the 45 degree angles, the legs have a ratio of 1. The hypotenuse has a ratio of square root of 2. To find what c equals, do 10 divided by square root of 2. C equals 5 square root of 2 for both legs.