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