Posted by
**COFFEE** on
.

Given two vectors, a and b, such that a + b = a - b, find the magnitude of b.

Consider the equation

a + b = a - b

to be n vector notation and both a and b have components. Subtract the a vector from both sides. You are left with

b = -b

That can only be true if b = 0. That would make its magnitude also zero.