A) 1
B) 2
C) 3
D) 4
Correct Answer: D
Solution :
\[{{D}^{r}}=i(1+\cos \theta )+\sin \theta =2i{{\cos }^{2}}\frac{\theta }{2}+2\sin \frac{\theta }{2}\cos \frac{\theta }{2}\] \ L.H.S \[={{\left[ \frac{\cos (\theta /2)+i\sin (\theta /2)}{i\cos (\theta /2)+\sin (\theta /2)} \right]}^{4}}\] = \[\frac{1}{{{i}^{4}}}{{(\cos \theta +i\sin \theta )}^{4}}=\cos 4\theta +i\sin 4\theta \].You need to login to perform this action.
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