o is the center of the regular pentagon ABCDE. How many degrees are there in OAB?

Please explain or show work

A.36
B.54
C.72
D.108
E.126

3 answers

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.
54
Correct! The answer is B. 54 degrees.