Firstly this shape is an triangle and a triangle has 3 sides/ angles and all angles sum up to 180 degrees...
E = 90 degrees
This explains that it is an hypotenuse triangle so...
answer:
= 39x39 = 1521
= 89x89 = 7921
= 1521 + 7921 = 9442
= square root of 9442 = 97.169954204 rounded off to 97.2
97.2 degrees!