MathDB

2001 KJMO P3

Source: 2001 KJMO P3

June 29, 2024

geometryincenter

Problem Statement

A

are points on circle

O

satisfying

\angle AOB < 120^{\circ}

.

C

is a point on the tangent line of

O

passing through

A

satisfying

AB=AC

and

\angle BAC < 90^{\circ}

.

D

is the intersection of

O

and

BC

not

B

, and

I

is the incenter of

ABD

. Prove that

AE=AC

where

E

is the intersection of

CI

and

AD

.

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