| 几何题 |
| 送交者: ultrasound 2006年01月06日22:59:27 于 [灵机一动] 发送悄悄话 |
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Take a piece of paper, fold one corner onto a point D' in the interior of the sheet of paper without moving the other corner along the same edge. Next fold the other corner onto the point C' which lies on the interior edge, as illustrated in the diagram. What is the angle PQR? Take a guess frist, then proof. |
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| 实用资讯 | |
