Question

Two vectors of equal magnitude have a resultant equal to either of them. Then, the angle between them will be $2\pi /3$ radians. The angle in degrees is:

• A. ${30}^{\circ }$
• B. ${120}^{\circ }$
• C. ${60}^{\circ }$
• D. ${45}^{\circ }$

Answer 1

Answer: (B)

${120}^{\circ }$

Angle $\theta$ in radians is equal to $\frac{180}{\pi }\times \theta$ in degrees.
Thus, $\frac{2\pi }{3}=\frac{180}{\pi }\times \frac{2\pi }{3}={120}^0$