MathDB
Some geometry

Source: St Petersburg Olympiad 2012, Grade 9, P6

September 29, 2017
geometry

Problem Statement

ABCABC is triangle. Point LL is inside ABCABC and lies on bisector of B\angle B. KK is on BLBL. KAB=LCB=α\angle KAB=\angle LCB= \alpha. Point PP inside triangle is such, that AP=PCAP=PC and APC=2AKL\angle APC=2\angle AKL. Prove that KPL=2α\angle KPL=2\alpha