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Isogonal lines at the intersection of two circles

Source: RMO Delhi 2016, P3

October 11, 2016

geometry

Problem Statement

Two circles

C_1

and

C_2

intersect each other at points

A

and

B

. Their external common tangent (closer to

B

) touches

C_1

at

P

and

C_2

at

Q

. Let

C

be the reflection of

B

in line

PQ

. Prove that

\angle CAP=\angle BAQ

.

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