Two vectors A→and B→ are such that A→+B→=A→-B→. The angle between the vectors A→ and B→ is :
0
π/3
π/2
π
A→+B→=A→−B→ ⇒ A2+B2+2ABcosθ=A2+B2-2ABcosθ ⇒ cosθ=0 ⇒ θ=π2.