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How to integrate tan(xy)dx ?

3 Answers

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  • Since you're integrating with respect to x, then you can treat y as a constant:

    tan(xy) * dx =>

    sin(xy) * dx / cos(xy)

    u = cos(xy)

    du = -y * sin(xy) * dx

    Now we're integrating:

    (-1 / y) * du / u =>

    (-1 / y) * ln( |u| ) + C =>

    (-1 / y) * ln( |cos(xy)| ) + C

  • Ray
    Lv 7
    1 decade ago

    -(1/y) ln [cos(xy)] + C

    Remember that y is an independent variable since we are integrating with respect to x.

  • ?
    Lv 6
    1 decade ago

    ∫ tan(xy) dx

    Note that y is behaving like a constant.

    ∫ [sin(xy)] / [cos(xy)] dx

    u = cos(xy)

    du = -ysin(xy) dx

    dx = -1/(ysin(xy)) du

    (-1/y) ∫ 1/u du

    (-1/y) ln|u|

    (-1/y)ln|cos(xy)| + C

    Done!

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