Integral de sqrt(1-(1/x)^2) dx

                            //         /1\          I                I*x             1      \
                            ||- I*acosh|-| + ---------------- - --------------  for ---- > 1|
  /                         ||         \x/          _________        _________      | 2|    |
 |                          ||                     /      1         /      1        |x |    |
 |      __________          ||               x*   /  -1 + --       /  -1 + --               |
 |     /        2           ||                   /         2      /         2               |
 |    /      /1\            ||                 \/         x     \/         x                |
 |   /   1 - |-|   dx = C + |<                                                              |
 | \/        \x/            ||         x                1              /1\                  |
 |                          ||   ------------- - --------------- + asin|-|       otherwise  |
/                           ||        ________          ________       \x/                  |
                            ||       /     1           /     1                              |
                            ||      /  1 - --    x*   /  1 - --                             |
                            ||     /        2        /        2                             |
                            \\   \/        x       \/        x                              /

$$\int \sqrt{1 - \left(\frac{1}{x}\right)^{2}}\, dx = C + \begin{cases} - \frac{i x}{\sqrt{-1 + \frac{1}{x^{2}}}} - i \operatorname{acosh}{\left(\frac{1}{x} \right)} + \frac{i}{x \sqrt{-1 + \frac{1}{x^{2}}}} & \text{for}\: \frac{1}{\left|{x^{2}}\right|} > 1 \\\frac{x}{\sqrt{1 - \frac{1}{x^{2}}}} + \operatorname{asin}{\left(\frac{1}{x} \right)} - \frac{1}{x \sqrt{1 - \frac{1}{x^{2}}}} & \text{otherwise} \end{cases}$$

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