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

Let the two vectors be A→ and B→ .  Then, magnitude of sum of A→ and B→ , |A→+B→|=A2+B2+2ABcosθ and magnitude of difference of A→ and B→ , |A→-B→|=A2+B2-2ABcosθ,|A→+B→|=|A→-B→| or A2+B2+2ABcosθ=A2+B2-2ABcosθ⇒4ABcosθ=0∵4AB≠0,  ∴cosθ=0 or θ=90°