El gráfico de la función cruce el eje Z con f = 0
o sea hay que resolver la ecuación:
$$\cos{\left(z \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje Z:
Solución analítica$$z_{1} = \frac{\pi}{2}$$
$$z_{2} = \frac{3 \pi}{2}$$
Solución numérica$$z_{1} = 32.9867228626928$$
$$z_{2} = 73.8274273593601$$
$$z_{3} = 4.71238898038469$$
$$z_{4} = 39.2699081698724$$
$$z_{5} = 95.8185759344887$$
$$z_{6} = 45.553093477052$$
$$z_{7} = 70.6858347057703$$
$$z_{8} = -10.9955742875643$$
$$z_{9} = -58.1194640914112$$
$$z_{10} = -23.5619449019235$$
$$z_{11} = 26.7035375555132$$
$$z_{12} = -26.7035375555132$$
$$z_{13} = -89.5353906273091$$
$$z_{14} = -387.986692718339$$
$$z_{15} = -17.2787595947439$$
$$z_{16} = -42.4115008234622$$
$$z_{17} = -61.261056745001$$
$$z_{18} = 92.6769832808989$$
$$z_{19} = -76.9690200129499$$
$$z_{20} = -92.6769832808989$$
$$z_{21} = -98.9601685880785$$
$$z_{22} = 61.261056745001$$
$$z_{23} = -54.9778714378214$$
$$z_{24} = 42.4115008234622$$
$$z_{25} = -64.4026493985908$$
$$z_{26} = 67.5442420521806$$
$$z_{27} = -7.85398163397448$$
$$z_{28} = 80.1106126665397$$
$$z_{29} = -14.1371669411541$$
$$z_{30} = 14.1371669411541$$
$$z_{31} = -1.5707963267949$$
$$z_{32} = 1.5707963267949$$
$$z_{33} = 29.845130209103$$
$$z_{34} = 10.9955742875643$$
$$z_{35} = 17.2787595947439$$
$$z_{36} = -51.8362787842316$$
$$z_{37} = -29.845130209103$$
$$z_{38} = -48.6946861306418$$
$$z_{39} = -73.8274273593601$$
$$z_{40} = 23.5619449019235$$
$$z_{41} = 20.4203522483337$$
$$z_{42} = -86.3937979737193$$
$$z_{43} = 54.9778714378214$$
$$z_{44} = -168.075206967054$$
$$z_{45} = 58.1194640914112$$
$$z_{46} = 51.8362787842316$$
$$z_{47} = -67.5442420521806$$
$$z_{48} = -4.71238898038469$$
$$z_{49} = -45.553093477052$$
$$z_{50} = -70.6858347057703$$
$$z_{51} = -2266.65909956504$$
$$z_{52} = 48.6946861306418$$
$$z_{53} = -83.2522053201295$$
$$z_{54} = -95.8185759344887$$
$$z_{55} = 89.5353906273091$$
$$z_{56} = -39.2699081698724$$
$$z_{57} = 76.9690200129499$$
$$z_{58} = -32.9867228626928$$
$$z_{59} = -20.4203522483337$$
$$z_{60} = -36.1283155162826$$
$$z_{61} = 7.85398163397448$$
$$z_{62} = -80.1106126665397$$
$$z_{63} = 86.3937979737193$$
$$z_{64} = 98.9601685880785$$
$$z_{65} = 36.1283155162826$$
$$z_{66} = 64.4026493985908$$
$$z_{67} = 83.2522053201295$$