Question

6.
If the magnitude of sum of two vectors is equal
the magnitude of difference of the two vectors.
angle between these vectors is :-
(1) 0°
(3) 45°
(4) 180°
(2) 90°

Answer 1

Answer:

See the above attachment for your answer

Answer 2

Answer:

(2) 90°

Explanation:

Let the two vectors be A and B with magnitudes A and B respectively. Then magnitude of their sum is given by:

∣A+B∣=√(A²+B²+2ABcosθ)→(1) (θ= angle between the vectors)

Magnitude of their difference is given by:

∣A−B∣=√(A²+B²−2ABcosθ)→(2)

As ∣A+B∣=∣A−B∣

⇒A²+B²+2ABcosθ=A²+B²−2ABcosθ

⇒4ABcosθ=0 or cosθ=0

⇒θ=90°