MathDB
SM//CL wanted, ABCD rectangle , <DAC = 60^o

Source: 2011 Saudi Arabia Pre-TST November 2.4

December 31, 2021
geometryrectangleparallel

Problem Statement

Let ABCDABCD be a rectangle of center OO, such that DAC=60o\angle DAC = 60^o. The angle bisector of DAC\angle DAC meets DCDC at SS. Lines OSOS and ADAD meet at LL and lines BLBL and ACAC meet at MM. Prove that lines SMSM and CLCL are parallel.