6. In the figure, ABCD and BFEC are parallelograms. Prove that
(a) AD//FE,
(b) AD = FE,
(c) AFED is a parallelogram.
12. In the figure ,ABCD is a parallelogram.Both AE and CF are perpendicular to the diagonal BD,and BE = FD.
(a) Prove that AE = CF
(b)Join AF and EC.Prove that AECF is a parallelogram.
求step,thx~~
一定要有完整啲step~~(一定要有(< sum of △)lee d公式!!)唔好亂做,一定要岩同埋要清楚(要睇得明你寫咩)!!!!thx~~
去LEE到就有圖:
http://www.uwants.com/viewthread.php?tid=11603862&extra=page%3D1