BCECE Engineering BCECE Engineering Solved Paper-2002

  • question_answer
    \[\int_{{}}^{{}}{\frac{\tan x}{\sec x+\tan x}dx}\]is equal to:

    A) \[x+\sec x+\tan x+c\]

    B)  \[x-\sec x+\tan x+c\]

    C)  \[x-\tan x+\sec x+c\]

    D)  none of the above

    Correct Answer: C

    Solution :

    Let \[I=\int_{{}}^{{}}{\frac{\tan x}{\sec x+\tan x}}dx\] \[=\int_{{}}^{{}}{\frac{\tan x(\sec x-\tan x)}{{{\sec }^{2}}x-{{\tan }^{2}}x}}dx\] \[=\int_{{}}^{{}}{(\sec x\tan x-{{\tan }^{2}}x)}\,dx\] \[=\int_{{}}^{{}}{\sec x\tan x\,dx-\int_{{}}^{{}}{({{\sec }^{2}}x-1)dx}}\] \[=\sec x-\tan x+x+c\]


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