RAJASTHAN ­ PET Rajasthan PET Solved Paper-2001

  • question_answer
    \[{{(\sin \theta +i\cos \theta )}^{n}}\] is equal to

    A)  \[{{i}^{n}}(i\sin \theta +\cos \theta )\]

    B)  \[(\sin n\theta +i\cos n\theta )\]

    C)  \[\cos n\left( \frac{\pi }{2}-\theta  \right)+i\sin n\left( \frac{\pi }{2}-\theta  \right)\]

    D)  \[\cos \theta +i\sin n\theta \]

    Correct Answer: C

    Solution :

     \[(\sin \theta +i\cos \theta )hn\] \[={{\left[ \cos \left( \frac{\pi }{2}-\theta  \right)+i\sin \left( \frac{\pi }{2}-\theta  \right) \right]}^{n}}\] \[=\cos n\left( \frac{\pi }{2}-\theta  \right)+i\sin n\left( \frac{\pi }{2}-\theta  \right)\]


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