If the hypotenuse has length x, what we're going to prove is that the shorter side which is opposite the 30 degree side has length x/2, and that the 60 degree side... the 60 degree side, or the side that's opposite the 60 degree angle I should say is going to be the (the square root of 3 x the shorter side.) so the square root of 3 times (x/2) that's going to be its length.