JEE Main & Advanced Mathematics Indefinite Integrals Question Bank Integration by Substitution

  • question_answer
    \[\int_{{}}^{{}}{\frac{\cos x-\sin x}{1+\sin 2x}\ dx=}\]       [AISSE 1985]

    A)            \[-\frac{1}{\cos x+\sin x}+c\]

    B)            \[\frac{1}{\cos x+\sin x}+c\]

    C)            \[\frac{1}{\cos x-\sin x}+c\]

    D)            None of these

    Correct Answer: A

    Solution :

                       \[\int_{{}}^{{}}{\frac{\cos x-\sin x}{1+\sin 2x}\,dx}=\int_{{}}^{{}}{\frac{\cos x-\sin x}{{{(\sin x+\cos x)}^{2}}}\,dx}\]            Now put \[\sin x+\cos x=t,\] then the required integral is                    \[-\frac{1}{\sin x+\cos x}+c\].


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