如图,已知圆锥侧面展开图的扇形面积为65πcm2,扇形的弧长为10πcm,则圆锥母线长是( )
A:5cm
B:10cm
C:12cm
D:13cm
4−1等于( )
— The driver couldn’t see the road clearly because of the heavy rain. This is the main reason.