Pythagorean theorem is a^2 + b^2 = c^2 2. You are trying to find x which is c^2 so plug in the other numbers to the other letters. 9^2 + 17^2 = c^2 9^2= 81. 17^2= 289 81 + 289 = 370 370= c^2 Now all you have to do is square root the number *square root sign* 370 19.24 c = 19.24 So, x = 19.24