Question

if the magnitude of sum of two vectors is equal to the magnitude of difference of the two vectors the angle between these vector is

a) 90 b) 45 c) 180 d)0

Answer 1

Here is the solution :

let the two vectors be a and b,

According to the question,

|a-b| = |a+b|,

from parallelogram law of vectors, we know that,

|p±q| = √(p² + q² ± 2pq cos ∆)

where, ∆ = angle between the vectors p and q,

=> √(a²+b²+2abcos∆) = √(a²+b²-2abcos∆)

squaring on both sides and cancelling a and b both sides,

=> 2abcos∆ = -2abcos∆

=> 4abcos∆ = 0,

|a| ≠ |b| ≠ 0,

=> cos∆ = 0,

=> ∆ = odd integral multiples of 90°,

=> ∆ = 90°, 270°...

since 270° isn't in the options given, (a) 90° will be the correct answer.

therefore , the angle between the 2 vectors is 90°.

Hope you understand, Thanking you,

Bunti 360!

Answer 2

Answer:

Explanation:

The correct answer is 180°...

Plz refer the attachment below. ...