最基本的知识.
过A做AE//CD,E在BC上.
角C=角AEB.
因为AB=CD,平行四边形CD=AE,所以AB=AE,等腰三角形ABE,角B=角AEB.
所以角A+角C=角A+角AEB=角A+角B=180°
如图,在梯形ABCD中,AD‖BC,AB=DC,试证明:∠A+∠C=180°
如图,在梯形ABCD中,AD‖BC,AB=DC,试证明:∠A+∠C=180°
A---------------、D
/ 、
B-----------------------------、C
A---------------、D
/ 、
B-----------------------------、C
数学人气:229 ℃时间:2019-10-29 13:25:54
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