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如图,AB是⊙O的直径,弦BC=2cm,F是弦BC的中点,∠ABC=60°.若动...
如图,AB是⊙O的直径,弦BC=2cm,F是弦BC的中点,∠ABC=60°.若动点E以2cm/s的速度从A点出发沿着A→B→A方向运动,设运动时间为t(s)(0≤t<3),连接EF,当△BEF是直角三角形时,t(s)的值为( )
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101192737361812104/SYS201311011927373618121007_ST/images0.png)
A.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101192737361812104/SYS201311011927373618121007_ST/0.png)
B.1
C.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101192737361812104/SYS201311011927373618121007_ST/1.png)
或1
D.
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101192737361812104/SYS201311011927373618121007_ST/2.png)
或1或
![manfen5.com 满分网](http://img.manfen5.com/res/CZSX/web/STSource/20131101192737361812104/SYS201311011927373618121007_ST/3.png)
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