MathDB
Incircle of curved triangle?

Source: Russian TST 2016, Day 8 P3 (Groups A & B)

April 19, 2023
geometrycircles

Problem Statement

Two circles ω1\omega_1 and ω2\omega_2 intersecting at points XX{} and YY{} are inside the circle Ω\Omega and touch it at points AA{} and BB{}, respectively; the segments ABAB and XYXY intersect. The line ABAB intersects the circles ω1\omega_1 and ω2\omega_2 again at points CC{} and DD{}, respectively. The circle inscribed in the curved triangle CDXCDX touches the side CDCD at the point ZZ{}. Prove that XZXZ is a bisector of AXB\angle AXB{}.