A) \[{{e}_{r}}=\cos \theta \,\hat{i}+\sin \theta \hat{j}\]
B) \[{{e}_{r}}=\tan \theta \,\hat{i}+\cot \theta \hat{j}\]
C) \[{{e}_{r}}=-\cos \theta \,\hat{i}-\sin \theta \hat{j}\]
D) \[{{e}_{r}}=(\sin \theta +\cos \theta )\hat{j}\]
E) \[{{e}_{r}}=\cos \theta \hat{j}\]
Correct Answer: A
Solution :
Consider the diagram given below From the figure \[\mathbf{PA}=\hat{i}\,PA\,\,\cos \theta +\hat{j}\,PA\,\,\sin \theta \] \[\frac{\mathbf{PA}}{PA}=\hat{i}\,\cos \theta +\hat{j}\,\,\sin \theta \]You need to login to perform this action.
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