过点D作DE∥BC交AB于E
∵等腰梯形ABCD
∴∠B=∠A=60
∵DE∥BC
∴∠DEA=∠B=60
∴等边△ADE
∴AE=AD=8
∴BE=AB-AE=20-8=12
∵AB∥CD,DE∥BC
∴平行四边形BCDE
∴CD=BE=12(cm)
数学辅导团解答了你的提问,
在等腰梯形ABCD中,AB平行CD,AB=20cm,AD=8cm,角A=60°,求CD的长
在等腰梯形ABCD中,AB平行CD,AB=20cm,AD=8cm,角A=60°,求CD的长
数学人气:999 ℃时间:2020-05-20 16:51:46
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