Let `|vec(a)|~=0, |vec(b)|~=0`
`(vec(a)+vec(b)).(vec(a)+vec(b))=|vec(a)|^(2)+|vec(b)|^(2)` holds if and only if

Let |vec(a)| # 0.|vec(b)| ne 0 (vec(a) + vec(b)). (vec(a) + vec(b)) = |vec(a)|^(2) + |vec(b)|^(2) holds if and only if

If |vec(a)|= |vec(b)| =1 and |vec(a) xx vec(b)|= vec(a).vec(b) , then |vec(a) + vec(b)|^(2)=

Prove that (vec(a)+vec(b)).(vec(a)+vec(b)) = |vec(a)|^(2) + |vec(b)|^(2) , if and only if vec(a) , vec(b) are perpendicular , given vec(a) 1= vec (0) , vec (b) != vec (0)

prove that (vec(a)+vec(b)).(vec(a)+vec(b))=|vec(a)|^(2)+|vec(b)|^(2) , if and only if vec(a),vec(b) are perpendicular, given vec(a) ne vec(0), vec(b) ne vec(0) .

If (vec(a)-vec(b)).(vec(a)+vec(b))=27 and |vec(a)|=2|vec(b)| the find |vec(a)| and |vec(b)| .

If (vec(a) + vec(b)) _|_ vec(b) and (vec(a) + 2 vec(b))_|_ vec(a) , then

If vec(a).vec(b)=0 and vec(a) xx vec(b)=0, " prove that " vec(a)= vec(0) or vec(b)=vec(0) .

If vec(a).vec(b)=0 and vec(a) xx vec(b)=0, " prove that " vec(a)= vec(0) or vec(b)=vec(0) .

If vec(a).vec(b)=0 and vec(a) xx vec(b)=0, " prove that " vec(a)= vec(0) or vec(b)=vec(0) .