In∆ABC, P&Q are the respective midpoints of AB&AC. Suppose PQ is extened to R so that PQ=QR. Prove RC║AB?

Answer 1

Here is a rough outline: First show that triangle apq is congruent to triangle crq ( using sas); after this use cpctc to show that angle p=angle r--meaning that line ab is parallel to line rc.

Answer 2

prove triangle apq is congurent to triangle to triangle qrc by sas test .so angle qrc is congurent to angle apq
so by alternate angle test the lines are parallel