If the magnitude of sum of two vectors is equal to the magnitude of difference of the two vectors, the angle between these vectors is:

Step-by-step solution

A → + B → = A → - B → A → 2 + B → 2 + 2 A → B →   cos θ = A → 2 + B → 2 - 2 A → B →   cos θ 4 A → B →   cos θ =0 cos θ = 0 θ = 90 °