Explanation: First things first, identify the hypotenuse. That is the longest side of the triangle and the one opposite to the right angle. Then, fill in the equation using substitution. 5 squared is 5(5) or 25 13 squared is 13(13) or 169 Now you have 25+b^2=169 Subtract 25 from 169 to get b^2=144 Now to even out the statement and get rid of the exponent, find the square root of 144. You will get b=12