Thứ Bảy, 13 tháng 9, 2014

55-Three point collinear again

Let ABC be quadrilateral, M, N are midpoints of AD,BC respectively. Three red parallel lines through B,M,C respectively meet three blue parallel lines through A,ND respectively at I,J,K. Show that I,J,K are collinear and the line IJK through fixed point when three parrallel line turn. Solution click:

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