Question

If two vectors and the value of their attainment ​​are equal, what is the angle between the two vectors?

correct answer will be 120°. ​

Answer 1

Answer :

Two vectors and their resultant have same magnitude.

We have to find angle between both vectors$.$

★ By triangle law or parallelogram law of vector addition, the magnitude of resultant R at two vectors A and B inclined to each other at angle θ, is given by

• R² = A² + B² + 2AB cosθ

Let magnitude of both vectors be x.

ATQ, resultant also have same magnitude.

• R = A = B = x

By substituting the values, we get

➝ x² = x² + x² + 2(x)(x) cosθ

➝ x² = 2x² + 2x² cosθ

➝ -x² = 2x² cosθ

➝ cosθ = -x²/2x²

➝ cosθ = -1/2

➝ θ = cos‾¹ (-1/2)

➝ θ = 120°