El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$\cot{\left(\frac{x}{3} \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = \frac{3 \pi}{2}$$
Solución numérica$$x_{1} = 14.1371669411541$$
$$x_{2} = -70.6858347057703$$
$$x_{3} = 32.9867228626928$$
$$x_{4} = 61.261056745001$$
$$x_{5} = -61.261056745001$$
$$x_{6} = 70.6858347057703$$
$$x_{7} = -80.1106126665397$$
$$x_{8} = 42.4115008234622$$
$$x_{9} = 51.8362787842316$$
$$x_{10} = -98.9601685880785$$
$$x_{11} = 80.1106126665397$$
$$x_{12} = 98.9601685880785$$
$$x_{13} = -89.5353906273091$$
$$x_{14} = 4.71238898038469$$
$$x_{15} = 89.5353906273091$$
$$x_{16} = -51.8362787842316$$
$$x_{17} = -14.1371669411541$$
$$x_{18} = -4.71238898038469$$
$$x_{19} = -32.9867228626928$$
$$x_{20} = 23.5619449019235$$
$$x_{21} = -23.5619449019235$$
$$x_{22} = -42.4115008234622$$