MathDB
IZhO 2024, P2

Source:

January 9, 2024
geometry

Problem Statement

Circles Ω\Omega and Γ\Gamma meet at points AA and BB. The line containing their centres intersects Ω\Omega and Γ\Gamma at point PP and QQ, respectively, such that these points lie on same side of the line ABAB and point QQ is closer to ABAB than point PP. The circle δ\delta lies on the same side of the line ABAB as PP and QQ, touches the segment ABAB at point DD and touches Γ\Gamma at point TT. The line PDPD meets δ\delta and Ω\Omega again at points KK and LL, respectively. Prove that QTK=DTL\angle QTK=\angle DTL