设平行四边形ABCD中,AC与BD交于0点,E是AD 中点,AE的延长线与CD交于点F,向量AC=a,BD=b,则向量AF=?2/3a+1/设平行四边形ABCD中,AC与BD交于0点,E是AD 中点,AE的延长线与CD交于点F,向量AC=a,BD=b,则向量AF=?2/3a+1/3b
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![设平行四边形ABCD中,AC与BD交于0点,E是AD 中点,AE的延长线与CD交于点F,向量AC=a,BD=b,则向量AF=?2/3a+1/设平行四边形ABCD中,AC与BD交于0点,E是AD 中点,AE的延长线与CD交于点F,向量AC=a,BD=b,则向量AF=?2/3a+1/3b](/uploads/image/z/5040956-20-6.jpg?t=%E8%AE%BE%E5%B9%B3%E8%A1%8C%E5%9B%9B%E8%BE%B9%E5%BD%A2ABCD%E4%B8%AD%2CAC%E4%B8%8EBD%E4%BA%A4%E4%BA%8E0%E7%82%B9%2CE%E6%98%AFAD+%E4%B8%AD%E7%82%B9%2CAE%E7%9A%84%E5%BB%B6%E9%95%BF%E7%BA%BF%E4%B8%8ECD%E4%BA%A4%E4%BA%8E%E7%82%B9F%2C%E5%90%91%E9%87%8FAC%3Da%2CBD%3Db%2C%E5%88%99%E5%90%91%E9%87%8FAF%3D%3F2%2F3a%2B1%2F%E8%AE%BE%E5%B9%B3%E8%A1%8C%E5%9B%9B%E8%BE%B9%E5%BD%A2ABCD%E4%B8%AD%2CAC%E4%B8%8EBD%E4%BA%A4%E4%BA%8E0%E7%82%B9%2CE%E6%98%AFAD+%E4%B8%AD%E7%82%B9%2CAE%E7%9A%84%E5%BB%B6%E9%95%BF%E7%BA%BF%E4%B8%8ECD%E4%BA%A4%E4%BA%8E%E7%82%B9F%2C%E5%90%91%E9%87%8FAC%3Da%2CBD%3Db%2C%E5%88%99%E5%90%91%E9%87%8FAF%3D%3F2%2F3a%2B1%2F3b)
设平行四边形ABCD中,AC与BD交于0点,E是AD 中点,AE的延长线与CD交于点F,向量AC=a,BD=b,则向量AF=?2/3a+1/设平行四边形ABCD中,AC与BD交于0点,E是AD 中点,AE的延长线与CD交于点F,向量AC=a,BD=b,则向量AF=?2/3a+1/3b
设平行四边形ABCD中,AC与BD交于0点,E是AD 中点,AE的延长线与CD交于点F,向量AC=a,BD=b,则向量AF=?2/3a+1/
设平行四边形ABCD中,AC与BD交于0点,E是AD 中点,AE的延长线与CD交于点F,向量AC=a,BD=b,则向量AF=?2/3a+1/3b(a,b为向量)
设平行四边形ABCD中,AC与BD交于0点,E是AD 中点,AE的延长线与CD交于点F,向量AC=a,BD=b,则向量AF=?2/3a+1/设平行四边形ABCD中,AC与BD交于0点,E是AD 中点,AE的延长线与CD交于点F,向量AC=a,BD=b,则向量AF=?2/3a+1/3b
“E是AD 中点,”打错或者印错.应该是:E是OD 中点.
如图,AF=t(2AE)=t(AO+AD), AO=a/2, AD=(a+b)/2
∴AF=ta+tb/2.①
AF=AC+sCD=a+s(b-a)=(1-s)a+sb.②
1-s=t, s=t/2. s=1/3 AF=(2/3)a+(1/3)b.