题目内容
如图,在梯形ABCD中,AD∥BC,对角线AC、BD交于点O,BE∥CD交CA延长线于点E.
求证:OC2=OA•OE.

求证:OC2=OA•OE.
证明:∵AD∥BC,∴
=
,
又∵BE∥CD,∴
=
,
∴
=
,
∴OC2=OA•OE.
| OC |
| OA |
| OB |
| OD |
又∵BE∥CD,∴
| OE |
| OC |
| OB |
| OD |
∴
| OC |
| OA |
| OE |
| OC |
∴OC2=OA•OE.
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