题目内容
已知的夹角是
A、30° B、45° C、90° D、135°
B
【解析】略
A.30° B.-150° C.150° D.30°或150°
已知△ABC中,=,=,·<0,S△ABC=,||=3,| |=5,则与的夹角是( )
A.30° B.-150° C.150° D.30°或150°
已知a·b=-3,则a与b的夹角是
A.150° B.30° C.60° D.120°
A.150° B.30° C.60° D.120°