如图,在梯形ABCD中,AD∥BC,AB=DC=AD,∠C=60°,AE⊥BD于点E,AE=1.求梯形ABCD的面积.
人气:110 ℃ 时间:2019-08-18 21:12:54
解答
过D作DF∥AB交BC于F,
∵AD∥BC,∴四边形ABFD是平行四边形,∴DF=AB,又AB=CD,
∴DF=CD,∵∠C=60°,∴ΔDFC是等边三角形,
∴∠ABC=60°,
∵AB=AD,∴ABFD是菱形,∠ADB=∠ABD,又∠ADB=∠CBD,
∴∠ABD=∠CBD=1/2∠ABC=30°,
∴AB=2AE=2,
∴SΔDFC=√3/4×2^2=√3,
又S菱形ABFD=2SΔDFC=2√3,
∴S梯形=S菱形ABFD+SΔDFC=3√3.
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