Pou�ijeme identitu
$$
\left (\sin(x)\right )^{3}={
\frac {3\,\sin(x)}{4}}-{\frac 
{\sin(3\,x)}{4}} \quad ,
$$
a dosad�me Taylor�v rozvoj funkce sinus
$$
\sum _{n=2}^{\infty }{\frac {\left (-1\right )
^{n-1}\left (3-{3}^{2\,n-1}\right ){x}^{2\,n-1
}}{\left (2\,n-1\right )!}}1/4 \quad .
$$
