Skip to main content
OlympiadHQ

Browse · MathNet

Print

Team Selection Test for EGMO 2019

Turkey 2019 geometry

Problem

Let be a triangle satisfying . Let be a point on smaller arc of circumcircle of . Let be the symmetric point of with respect to the line . The line intersects at . The tangent line of at intersects the line at and the lines and intersect at . Show that the points are collinear.

problem
Solution
Let be a point on such that . Since , we conclude that the points , , are collinear.



Using Pascal theorem for the points , , , , , , we find that the points , , are collinear, and we are done. (Here denotes the tangent line of at .)

Techniques

TangentsAngle chasing