A) \[-\frac{1}{2}\mathbf{i}+\frac{\sqrt{3}}{2}\mathbf{j}\]
B) \[-\frac{\sqrt{3}}{2}\mathbf{i}+\frac{1}{2}\mathbf{j}\]
C) \[\frac{1}{2}\mathbf{i}+\frac{\sqrt{3}}{2}\mathbf{j}\]
D) \[\frac{\sqrt{3}}{2}\mathbf{i}-\frac{1}{2}\mathbf{j}\]
Correct Answer: C
Solution :
\[\mathbf{b}=\cos 120{}^\circ \mathbf{i}+\sin 120{}^\circ \mathbf{j}\] or \[\mathbf{b}=-\frac{1}{2}\mathbf{i}+\frac{\sqrt{3}}{2}\mathbf{j}.\] Therefore \[\mathbf{a}+\mathbf{b}=\mathbf{i}-\frac{1}{2}\mathbf{i}+\frac{\sqrt{3}}{2}\mathbf{j}=\frac{1}{2}\mathbf{i}+\frac{\sqrt{3}}{2}\mathbf{j}\].
You need to login to perform this action.
You will be redirected in
3 sec
