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