Please help! I need to find angle A of both triangles and I don’t understand how.

Ok so the formula is a^2 + b^2 = c^2 or a squared plus b squared equals c squared so you grab the numbers and input them so it would be 13^2 + 28^2= c^2 . 13 squared is 169 and 28 squared is 784 then you add them so that would = to 953 ,but that’s not your answer since you still have 953 squared you need to take the ^2 off so you have to find the square root of 953 use the radical symbol on a calculator specificity the one with 2 then you get your answer which is a or x=30.87 if you have to round to the nearest 10th it would be 30.9 if not keep it as 30.87 the 2nd answer is x or a=51.47 :)