The vectors A and B are such that lA+Bl=lA-Bl then the angle between the two vectors will be
0°
60°
90°
180°
Given that lA+Bl=lA-BI∴ A2 + B2 + 2A Bcos θ = A2 + B2 -2 ABcos θor 4ABcosθ=0 or cosθ=0,θ = 90°