如图,在直角梯形ABCD中,AD‖BC,AB=DC=AD,AC⊥AB,将CB延长致点F,使BF=CD 求∠ABC的度数
人气:423 ℃ 时间:2019-08-18 00:43:17
解答
∵AB = CD
∴∠ABC = ∠DCB
∵AD = DC
∴∠DAC = ∠DCA
∵AD//BC
∴∠DAC = ∠ACB
∴AC是∠DCB的角平分线
∵∠ABC = ∠DCB
∴∠ABC :∠ACB = 2:1
∵AC ⊥ AB
∴∠ABC = 60°,∠ACB = 30°
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