Primitive of Square of Cotangent of a x

Theorem

$\ds \int \cot^2 a x \rd x = \frac {-\cot a x} a - x + C$


Proof

\(\ds \int \cot^2 x \rd x\) \(=\) \(\ds -\cot x - x\) Primitive of $\cot^2 x$
\(\ds \leadsto \ \ \) \(\ds \int \cot a x \rd x\) \(=\) \(\ds \frac 1 a \paren {-\cot a x - a x} + C\) Primitive of Function of Constant Multiple
\(\ds \) \(=\) \(\ds \frac {-\cot a x} a - x + C\) simplifying

$\blacksquare$


Also see


Sources

  • 1968: Murray R. Spiegel: Mathematical Handbook of Formulas and Tables ... (previous) ... (next): $\S 14$: Integrals involving $\cot a x$: $14.441$
  • 1968: George B. Thomas, Jr.: Calculus and Analytic Geometry (4th ed.) ... (previous) ... (next): Back endpapers: A Brief Table of Integrals: $85$.
  • 2009: Murray R. Spiegel, Seymour Lipschutz and John Liu: Mathematical Handbook of Formulas and Tables (3rd ed.) ... (previous) ... (next): $\S 17$: Tables of Special Indefinite Integrals: $(21)$ Integrals Involving $\cot a x$: $17.21.2.$