Let's use the pythagorean theorem, which is a^2 + b^2=c^2
C^2 is always going to be the hypotenuse, so the rest of the order doesn't really matter. 11^2 is 121 and 4^2 is 16, added together it's 137. Then you just need to find the square root of that, it's 11.7046999107. Just round it to the nearest hundreth, which is 11.70.