Two circles with centers P and Q intersect at A and B (see figure below).
AP extended meets circle P at C and circle Q at D. AQ extended
meets circle P at E and circle Q at F. Prove than points B, P,
E, D, and Q are concyclic.
This entry contributed by Sumith Peiris, Moratuwa, Sri Lanka.
Geometry Problem 1233 in Motion
Click on the figure below.