MathDB

tangent to first circle at A is parallel to BC

Source: Switzerland - Swiss TST 1999 p1

February 19, 2020

intersecting circlestangentparallelgeometry

Problem Statement

Two circles intersect at points

M

and

N

. Let

A

be a point on the first circle, distinct from

M,N

. The lines

AM

and

AN

meet the second circle again at

B

and

C

, respectively. Prove that the tangent to the first circle at

A

is parallel to

BC