Integral Calculus Question 109

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

[Roorkee 1976]

Options:

A) $ \log \sin 2x+c $

B) $ \log (1+{{\sin }^{2}}x)+c $

C) $ \frac{1}{2}\log (1+{{\sin }^{2}}x)+c $

D) $ {{\tan }^{-1}}(\sin x)+c $

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Answer:

Correct Answer: B

Solution:

Put $ (1+{{\sin }^{2}}x)=t\Rightarrow \sin 2x,dx=dt $ Hence $ \int_{{}}^{{}}{\frac{\sin 2x}{1+{{\sin }^{2}}x}dx}=\int_{{}}^{{}}{\frac{1}{t}dt=\log (1+{{\sin }^{2}}x)+c.} $