V(A-B)= (1+1)i +(1+1)j+ (1+1)k
Angle between two vectors is given as
cosФ= V(A-B).V(A) / IV(A-B)I IV(A)I
where V(A-B).V(A) means scalar product or the dot product and
IV(A-B)I IV(A)I means product of modulus of vector V(A-B) and V(A) respectively.
Hence from this we get
cosФ= 2*1+2*1+2*1 / (√2²+2²+2²)(√1²+1²+1²)
cosФ=1 at 0°,180°