Integraal van $$$\sqrt{\cot{\left(x \right)}} \csc^{2}{\left(x \right)}$$$

Bepaal $$$\int \sqrt{\cot{\left(x \right)}} \csc^{2}{\left(x \right)}\, dx$$$.

Zij $$$u=\cot{\left(x \right)}$$$.

Dan $$$du=\left(\cot{\left(x \right)}\right)^{\prime }dx = - \csc^{2}{\left(x \right)} dx$$$ (de stappen zijn te zien »), en dan geldt dat $$$\csc^{2}{\left(x \right)} dx = - du$$$.

Dus,

$${\color{red}{\int{\sqrt{\cot{\left(x \right)}} \csc^{2}{\left(x \right)} d x}}} = {\color{red}{\int{\left(- \sqrt{u}\right)d u}}}$$

Pas de constante-veelvoudregel $$$\int c f{\left(u \right)}\, du = c \int f{\left(u \right)}\, du$$$ toe met $$$c=-1$$$ en $$$f{\left(u \right)} = \sqrt{u}$$$:

$${\color{red}{\int{\left(- \sqrt{u}\right)d u}}} = {\color{red}{\left(- \int{\sqrt{u} d u}\right)}}$$

Pas de machtsregel $$$\int u^{n}\, du = \frac{u^{n + 1}}{n + 1}$$$ $$$\left(n \neq -1 \right)$$$ toe met $$$n=\frac{1}{2}$$$:

$$- {\color{red}{\int{\sqrt{u} d u}}}=- {\color{red}{\int{u^{\frac{1}{2}} d u}}}=- {\color{red}{\frac{u^{\frac{1}{2} + 1}}{\frac{1}{2} + 1}}}=- {\color{red}{\left(\frac{2 u^{\frac{3}{2}}}{3}\right)}}$$

We herinneren eraan dat $$$u=\cot{\left(x \right)}$$$:

$$- \frac{2 {\color{red}{u}}^{\frac{3}{2}}}{3} = - \frac{2 {\color{red}{\cot{\left(x \right)}}}^{\frac{3}{2}}}{3}$$

Dus,

$$\int{\sqrt{\cot{\left(x \right)}} \csc^{2}{\left(x \right)} d x} = - \frac{2 \cot^{\frac{3}{2}}{\left(x \right)}}{3}$$

Voeg de integratieconstante toe:

$$\int{\sqrt{\cot{\left(x \right)}} \csc^{2}{\left(x \right)} d x} = - \frac{2 \cot^{\frac{3}{2}}{\left(x \right)}}{3}+C$$

$$$\int \sqrt{\cot{\left(x \right)}} \csc^{2}{\left(x \right)}\, dx = - \frac{2 \cot^{\frac{3}{2}}{\left(x \right)}}{3} + C$$$A