高中数学，射影与投影有什么区别？哪个有正负之分？ 数学投影是否有正负？射影是否有正负？
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2. \u5173\u4e8e\u6295\u5f71\uff1a
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3. \u603b\u7ed3\uff1a\u5bf9\u4e8e\u6ca1\u6709\u65b9\u5411\u7684\u5f62\u4f53\uff0c\u5176\u6295\u5f71\u6216\u5c04\u5f71\u5c31\u6ca1\u6709\u6b63\u8d1f\u4e4b\u5206\uff1b\u6709\u65b9\u5411\u7684\u5f62\u4f53\uff0c\u5176\u6295\u5f71\u6216\u5c04\u5f71\u5c31\u6709\u6b63\u8d1f\u6216\u6709\u65b9\u5411\u3002
1. \u5173\u4e8e\u5c04\u5f71\uff1a
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2. \u5173\u4e8e\u6295\u5f71\uff1a
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射影是一点发散投射，投影是平行光线投射。射影有方向，因此有正负之分。
一个是数，一个是向量，它们都有正负之分。
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