设向量a,b满足ab=3,[a]=3,[b]=2 (1)求(2)求|a-b|求大神帮助
问题描述:
设向量a,b满足ab=3,[a]=3,[b]=2 (1)求(2)求|a-b|求大神帮助
答
(1)cos=ab/[a][b]=1/2 所以=π/3 (2)|a-b|=根号(a-b)^2=根号([a]^2+[b]^2-2ab)=根号(9+4-2*3)=根号7