posted by Johnny .
o is the center of the regular pentagon ABCDE. How many degrees are there in OAB?
Please explain or show work
divide 360 into 5 equal parts. What do you get? 72.
But, that is angle AOB, the vertex of an isosceles triangle. So, each of the base angles (OAB and OBA) is (180-72)/2 = 54.