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Establish the integral formula for arccsc x

Establish that the following integration formula is correct:

    \[ \int \operatorname{arccsc} x \, dx = x \operatorname{arccsc} x + \frac{x}{|x|} \log \left| x  \sqrt{x^2-1} \right| + C. \]


Proof. We integrate by parts, letting

    \begin{align*}  u &= \operatorname{arccsc} x & du &= \frac{-1}{|x| \sqrt{x^2-1}} \, dx \\  dv &= dx & v &= x. \end{align*}

(Where we established the formula for the derivative of \operatorname{arccsc} x in this exercise, Section 6.22, Exercise #5). Therefore,

    \[ \int \operatorname{arccsc} x \, dx = x \operatorname{arccsc} x + \int \frac{x}{|x| \sqrt{x^2-1}} \, dx. \]

In the previous exercise we showed that

    \[ \int \frac{x}{|x| \sqrt{x^2-1}} \, dx = \frac{x}{|x|} \log \left| x + \sqrt{x^2-1} \right| + C. \]

Therefore,

    \[ \int \operatorname{arccsc} x \, dx = x \operatorname{arccsc} x + \frac{x}{|x|} \log \left| x + \sqrt{x^2-1} \right| + C. \]

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