A:0个
B:1个
C:2个
D:1个或2个
Yesterday it rained heavily when school was over. So we _______ stay in our classroom.
如图,将两块直角三角板的直角顶点C叠放在一起,
(1)若∠DCB=35°,求∠ACB的度数;
(2)若∠ACB=140°,求∠DCE的度数.
三个大小相同的力a→、b→、c→作用在同一物体P上,使物体P沿a→方向作匀速运动,设PA→=a→,PB→=b→,PC→=c→,试判断△ABC的形状.