Step-by-step explanation: To solve this we are going to need to understand the pythagorean theorem. we can use it as a way to find this certain side. if we put these numbers in the theorem, we get a^2+49=81 (7^2=49 and 9^2=81), we can subtract 49 on both sides and get 32. We would also need to take out the power of 2 on the side of the a^2, so you would do the square root of a^2, which would just become a and the square root of 32, which if you crunch the numbers on a calculator. You would get 5.656..... then you round it to the nearest tenth and get 5.7.
