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如图,将半径为2,圆心角为60°的扇形纸片AOB,在直线l上向右作无滑动的滚动至...
如图,将半径为2,圆心角为60°的扇形纸片AOB,在直线l上向右作无滑动的滚动至扇形A′O′B′处,则顶点O经过的路线总长为
.
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