IN ACUTE TRIANGLE ABC, CD IS BISECTOR OF ∠C, O IS THE CIRCUMCENTE...

12.

In acute triangle ABC, CD is bisector of

∠

C, O is the circumcenter. The

perpendicular from C to AB meets line OD in a point lying on the circumcircle of

AOB. Find

∠

C, in degree.

C

O

A

B

D

E

Answer :

^°

2011 Asia Inter-Cities Teenagers Mathematics Olympiad

Page 3

Section B.

Answer the following 3 questions. Show your detailed solution on the space

provided after each question. Each question is worth 20 points.