A:They are on Mum's nose.
B:They are on the desk.
I have a new basketball. Do you have ___________?
用下列词语造句
①缉拿 ②束手无策
如图,以△ABC的边AB为直径作⊙O,⊙O与边BC的交点D恰为BC边的中点,过点D作DE⊥AC于点E.
(I)求证:DE是⊙O的切线;
(Ⅱ)若∠B=30°,求AEDC的值.
半径为5cm的圆中,圆心角为72°的扇形面积为____ cm2.