MathDB

G3

Part of 2015 Indonesia MO Shortlist

Problems(1)

from 3 points of circumcircle, two tangents to incircle, means one more

Source: INAMO Shortlist 2015 G3

5/14/2019
Given ABCABC triangle with incircle L1L_1 and circumcircle L2L_2. If points X,Y,ZX, Y, Z lie on L2L_2, such that XY,XZXY, XZ are tangent to L1L_1, then prove that YZYZ is also tangent to L1L_1.
geometrycircumcircleTangentsincircle