Question

Given :$\overrightarrow{R} = \overrightarrow{A} + \overrightarrow{B}$ and R = A = B. The angle between $\overrightarrow{A}$ and $\overrightarrow{B}$ is–

• A. $60^{0}$
• B. $90^{0}$
• C. $120^{0}$
• D. $180^{0}$

Answer 1

Answer: (C)

$120^{0}$

Answer 2

R = $\sqrt{A^{2} + B^{2} + 2AB\cos\theta}$

given R = A = B

A² = A² + A² + 2A (1) cos q

cos = –1/2

$\theta = 120^{0}$s