已知向量a=(cos3x/2,sin3x/2),向量b=(cosx/2,-sinx/2),向量c=(根号3,-1)
问题描述:
已知向量a=(cos3x/2,sin3x/2),向量b=(cosx/2,-sinx/2),向量c=(根号3,-1)
(1)当a⊥b时,求x的值的集合;
(2)求|a-c|的最大值.
答
(1)a⊥b=> a.b=0(cos(3x/2),sin(3x/2).(cos(x/2),-sin(x/2))=0cos(3x/2)cos(x/2)-sin(3x/2)sin(x/2)=0cos2x=02x = nπ+π/2x = nπ/2 + π/4 n=0,1,2,...x的值的集合 = { x | x= nπ/2 + π/4,n=0,1,2,.}(2)a-c = ( ...