Question 971107
You have the right idea. However, we are looking for 'b' if you made a = 9.



a^2 + b^2 = c^2


9^2 + b^2 = 15^2


81 + b^2 = 225


b^2 = 225-81 ... Subtract 81 from both sides.


b^2 = 144


b = sqrt(144) ... Take the square root of both sides (note: b > 0)


b = 12



So the length is <font color="red">12 inches</font>