Primitive of Square of Hyperbolic Cotangent Function

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Theorem

$\ds \int \coth^2 x \rd x = x - \coth x + C$

where $C$ is an arbitrary constant.


Proof

\(\ds \int \coth^2 x \rd x\) \(=\) \(\ds \int \paren {1 + \csch^2 x} \rd x\) Difference of Squares of Hyperbolic Cotangent and Cosecant
\(\ds \) \(=\) \(\ds \int 1 \rd x + \int \csch^2 x \rd x\) Linear Combination of Primitives
\(\ds \) \(=\) \(\ds \int 1 \rd x - \coth x + C\) Primitive of Square of Hyperbolic Cosecant Function
\(\ds \) \(=\) \(\ds x - \coth x + C\) Primitive of Constant

$\blacksquare$


Sources