If you had not writted this answer,I would have not written

following solution as I'm busy this week.
We should now that all geometry theory can be proved by Ana.Geometry.
Let OA (OY),OC (OX),WE HAVE:A1(0,A1'),A2(0,A2'),B1(B1,B1'),B2(B2,B2'),C1(C1,0)AND C2(C2,0)
P((A2-A1')/[(A1'-B1)/B1-(A2'-B1')/B2],(A1'-B1')(A2'-A1')/[(A1'-B1)/B1-(A2'-B1')/B2+A1'),Q(....) R(....).WE GET THE POINS,WE GET SLOPES.THE SLOPES OF PQ AND PR ARE THE SAME,SO,...OK
I GOT P'S ORDIN...,I TIRED,I THINK YOU CAN GET IT.
Thank your question.