Integral Calculus Question 267

Question: $ \int_{{}}^{{}}{\sqrt{1+\sin \frac{x}{2}}\ dx=} $

[IIT 1980; MP PET 1989; Pb. CET 2003]

Options:

A) $ \frac{1}{4}( \cos \frac{x}{4}-\sin \frac{x}{4} )+c $

B) $ 4( \cos \frac{x}{4}-\sin \frac{x}{4} )+c $

C) $ 4( \sin \frac{x}{4}-\cos \frac{x}{4} )+c $

D) $ 4( \sin \frac{x}{4}+\cos \frac{x}{4} )+c $

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Answer:

Correct Answer: C

Solution:

$ \int_{{}}^{{}}{\sqrt{1+\sin \frac{x}{2},}}dx=\int_{{}}^{{}}{\sqrt{( {{\sin }^{2}}\frac{x}{4}+{{\cos }^{2}}\frac{x}{4}+2\sin \frac{x}{4}\cos \frac{x}{4} )},dx} $ $ =\int_{{}}^{{}}{( \sin \frac{x}{4}+\cos \frac{x}{4} ),dx=4( \sin \frac{x}{4}-\cos \frac{x}{4} )}+c $ .