Applicare la formula: $\int\cos\left(ax\right)dx$$=\frac{1}{a}\sin\left(ax\right)+C$, dove $a=9$

Applicare la formula: $\left[x\right]_{a}^{b}$$=eval\left(x,b\right)-eval\left(x,a\right)+C$, dove $a=-\pi $, $b=\pi $ e $x=\frac{1}{9}\sin\left(9x\right)$

Applicare la formula: $\frac{a}{b}c$$=\frac{ca}{b}$, dove $a=1$, $b=9$, $c=-1$, $a/b=\frac{1}{9}$ e $ca/b=- \left(\frac{1}{9}\right)\sin\left(9\cdot -\pi \right)$

Applicare l'identità trigonometrica: $\sin\left(nx\right)$$=-\sin\left(x\left|n\right|\right)$, dove $x=9$ e $n=-\pi $