Integral Calculus Question 333

Question: $ \int_{{}}^{{}}{\sqrt{1+\cos x}\ dx} $ equals

[RPET 1996]

Options:

A) $ 2\sqrt{2}\sin \frac{x}{2}+c $

B) $ -2\sqrt{2}\sin \frac{x}{2}+c $

C) $ -2\sqrt{2}\cos \frac{x}{2}+c $

D) $ 2\sqrt{2}\cos \frac{x}{2}+c $

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Answer:

Correct Answer: A

Solution:

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