Question

if |A×B|=A.B then |A+B| is equal to

Answer 1

If we consider θ to be the angle between the vectors A and B,

by defination of cross product and dot product,

AxB= |A||B|sinθ n̂

A.B = |A||B|cosθ

Edit

Thanks for the correction from the community.

AxB is a vector and A.B is a scalar, which can't be equal. The question should have been with

| AxB | = A.B

Considering the correction,

| AxB | = A.B can be only possible when sinθ = cosθ ,

which is so for θ=π/4 radians.

Therfore, the angle between A and B is π/4 

Answer 2

the answer is A+B

hope it helps u