Online Geometry Problem 770: Parallelogram, Angle
Bisector, Triangle, Circumcenter, Circle, Circumcircle, Angle
Measurement. Level: High School, College,
Mathematics Education

The figure shows a parallelogram ABCD, the
bisector of angle A meets CD at E and BC extended at F. If O is the
circumcenter of triangle CEF and the measure of angle BOD is 72 degrees,
find the measure of angle DBO.