using SOHCAHTOA we can see that we need to use cos because the sides that are given are the adjacent side and the hypotenuse so u have to divide the adjacent by the hypotenuse which is 8.8/13 and you should get 0.8 after you round to the nearest tenth and then you use your calculator to do cos^-1 (0.8) and you get 36.9 after you round to the nearest tenth of a degree