(向量)|a|=4,|b|=5,a与b夹角为60°,求|3a-b|
问题描述:
(向量)|a|=4,|b|=5,a与b夹角为60°,求|3a-b|
答
|3a-b| =根号下(9A2-6A*B+B2)=根号下(49)=7
答
109
(向量)|a|=4,|b|=5,a与b夹角为60°,求|3a-b|
|3a-b| =根号下(9A2-6A*B+B2)=根号下(49)=7
109