如图,点C在∠AOB的边OB上,用尺规作出了∠BCN=∠AOC,作图痕迹中,弧FG是( )
A:以点C为圆心,OD为半径的弧
B:以点C为圆心,DM为半径的弧
C:以点E为圆心,OD为半径的弧
D:以点E为圆心,DM为半径的弧
Sally took a photo of her friends while they _________ computer games.
(Ⅰ)以坐标原点为极点,x轴正半轴为极轴建立极坐标系,求C的极坐标方程;
(Ⅱ)直线l的参数方程是 {x=tcosαy=tsinα (t为参数),l与C交与A,B两点,|AB|= 10 ,求l的斜率.