题目内容
如图,梯形ABCD中AD∥BC,对角线AC、BD相交于点O,若AO∶CO=2∶3,AD=4,则BC等于( )
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A.12 B.8 C.7 D.6
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A.12 B.8 C.7 D.6
D
∵梯形ABCD中AD∥BC,
∴∠ADO=∠OBC,∠AOD=∠BOC,
∴△AOD∽△COB,∵AO∶CO=2∶3,AD=4,
∴
=
=
,∴
=
,解得BC=6.
故选D.
∴∠ADO=∠OBC,∠AOD=∠BOC,
∴△AOD∽△COB,∵AO∶CO=2∶3,AD=4,
∴
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故选D.
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