\((1)\)求\(a\)与\(b\)的夹角\(θ\);
\((2)\)求\((\)\(a\)\(-2\)\(b\)\()·\)\(b\);
\((3)\)当\(λ\)为何值时,向量\(λa\)\(+\)\(b\)与向量\(a\)\(-3\)\(b\)互相垂直?
进入组卷