OA 、OC、OD、OE等都表示向量,t表示倍数已知3OA=OC,2OB=OD,OE=t (OA+OB),则实数t为何值时,C、D、E 三点在同一条直线上?因为OA=1/3OC,OB=1/2OD,所以OE=t/3 OC+t/2 OD,当且仅当t/3+t/2=1时C、D、E三点共线.故t=6/5,
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![OA 、OC、OD、OE等都表示向量,t表示倍数已知3OA=OC,2OB=OD,OE=t (OA+OB),则实数t为何值时,C、D、E 三点在同一条直线上?因为OA=1/3OC,OB=1/2OD,所以OE=t/3 OC+t/2 OD,当且仅当t/3+t/2=1时C、D、E三点共线.故t=6/5,](/uploads/image/z/4113419-59-9.jpg?t=OA+%E3%80%81OC%E3%80%81OD%E3%80%81OE%E7%AD%89%E9%83%BD%E8%A1%A8%E7%A4%BA%E5%90%91%E9%87%8F%2Ct%E8%A1%A8%E7%A4%BA%E5%80%8D%E6%95%B0%E5%B7%B2%E7%9F%A53OA%3DOC%2C2OB%3DOD%2COE%3Dt+%EF%BC%88OA%2BOB%EF%BC%89%2C%E5%88%99%E5%AE%9E%E6%95%B0t%E4%B8%BA%E4%BD%95%E5%80%BC%E6%97%B6%2CC%E3%80%81D%E3%80%81E+%E4%B8%89%E7%82%B9%E5%9C%A8%E5%90%8C%E4%B8%80%E6%9D%A1%E7%9B%B4%E7%BA%BF%E4%B8%8A%3F%E5%9B%A0%E4%B8%BAOA%3D1%2F3OC%2COB%3D1%2F2OD%2C%E6%89%80%E4%BB%A5OE%3Dt%2F3+OC%2Bt%2F2+OD%2C%E5%BD%93%E4%B8%94%E4%BB%85%E5%BD%93t%2F3%2Bt%2F2%3D1%E6%97%B6C%E3%80%81D%E3%80%81E%E4%B8%89%E7%82%B9%E5%85%B1%E7%BA%BF.%E6%95%85t%3D6%2F5%2C)
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OA 、OC、OD、OE等都表示向量,t表示倍数已知3OA=OC,2OB=OD,OE=t (OA+OB),则实数t为何值时,C、D、E 三点在同一条直线上?因为OA=1/3OC,OB=1/2OD,所以OE=t/3 OC+t/2 OD,当且仅当t/3+t/2=1时C、D、E三点共线.故t=6/5,
OA 、OC、OD、OE等都表示向量,t表示倍数
已知3OA=OC,2OB=OD,OE=t (OA+OB),则实数t为何值时,C、D、E 三点在同一条直线上?
因为OA=1/3OC,OB=1/2OD,所以OE=t/3 OC+t/2 OD,当且仅当t/3+t/2=1时
C、D、E三点共线.故t=6/5
,我不明白的就是为什么要t/3+t/2=1,
OA 、OC、OD、OE等都表示向量,t表示倍数已知3OA=OC,2OB=OD,OE=t (OA+OB),则实数t为何值时,C、D、E 三点在同一条直线上?因为OA=1/3OC,OB=1/2OD,所以OE=t/3 OC+t/2 OD,当且仅当t/3+t/2=1时C、D、E三点共线.故t=6/5,
3OA=OC,2OB=OD,OE=t (OA+OB)
OA=(1/3)OC,OB=(1/2)OD
OE=t/3OC+ t/2OD
if E is on CD,then
let |CE|/|EC| = m:n
=> OE = (nCE +mEC)/(m+n)
Now
OE=t/3OC+ t/2OD
m+n = 1
n+m = (t/3) + (t/2) = 1