Given that vectors p and q, p+q=p-q. This is true when

Question

1. p=q

2. q=0

3. neither p nor q is null vector

4. p is perpendicular to q

Answer 1

(A²+B²+2ABCOSø)^1/2=(A²+B²-2ABCOSø)^1/2​

So COSø=0

Ø=90°

Option D is correct..