If `|vec(a) + vec(b)| = |vec(a) - vec(b)|` then

Options

A. `|a|=|b|ne0`
B. `vec(a)` is perpendicular to `vec(b)`
C. `|a|=|b|ne0` and `vec(a)` and `vec(b)` are parallel and antiparallel
D. when either of |a| or |b| is zero

Answer

B

Explanation

Here
`|vec(a)+vec(b)|=sqrt(a^(2)+b^(2)2abcostheta)`
and `|vec(a)-vec(b)|=sqrt(a^(2)+b^(2)-2abcostheta)`
When `theta=90^@,costheta=0`
and `|vec(A)+vec(b)|=|vec(a)-vec(b)|`