El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$- \cos^{2}{\left(x \right)} + \cos{\left(x \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = 0$$
$$x_{2} = \frac{\pi}{2}$$
$$x_{3} = \frac{3 \pi}{2}$$
$$x_{4} = 2 \pi$$
Solución numérica$$x_{1} = 51.8362787842316$$
$$x_{2} = -36.1283155162826$$
$$x_{3} = 4.71238898038469$$
$$x_{4} = 69.1150379836781$$
$$x_{5} = 89.5353906273091$$
$$x_{6} = 12.5663704623094$$
$$x_{7} = -18.8495562409837$$
$$x_{8} = 25.1327418085792$$
$$x_{9} = 36.1283155162826$$
$$x_{10} = 75.3982238342404$$
$$x_{11} = 69.1150385134118$$
$$x_{12} = -4.71238898038469$$
$$x_{13} = -42.4115008234622$$
$$x_{14} = 18.8495557729205$$
$$x_{15} = -62.8318534973011$$
$$x_{16} = -69.115038497193$$
$$x_{17} = 6.28318528429551$$
$$x_{18} = -80.1106126665397$$
$$x_{19} = 7.85398163397448$$
$$x_{20} = 39.2699081698724$$
$$x_{21} = -29.845130209103$$
$$x_{22} = -43.9822971746199$$
$$x_{23} = 76.9690200129499$$
$$x_{24} = -23.5619449019235$$
$$x_{25} = 62.8318529132021$$
$$x_{26} = -75.3982238479311$$
$$x_{27} = -17.2787595947439$$
$$x_{28} = 43.9822971693881$$
$$x_{29} = 14.1371669411541$$
$$x_{30} = -389.557489134924$$
$$x_{31} = -100.530964736174$$
$$x_{32} = 58.1194640914112$$
$$x_{33} = 61.261056745001$$
$$x_{34} = -51.8362787842316$$
$$x_{35} = -39.2699081698724$$
$$x_{36} = 80.1106126665397$$
$$x_{37} = -92.6769832808989$$
$$x_{38} = -6.28318514935383$$
$$x_{39} = 64.4026493985908$$
$$x_{40} = -20.4203522483337$$
$$x_{41} = -98.9601685880785$$
$$x_{42} = 25.1327408583892$$
$$x_{43} = 0$$
$$x_{44} = -58.1194640914112$$
$$x_{45} = -50.2654823051418$$
$$x_{46} = 86.3937979737193$$
$$x_{47} = -54.9778714378214$$
$$x_{48} = 10.9955742875643$$
$$x_{49} = -14.1371669411541$$
$$x_{50} = -48.6946861306418$$
$$x_{51} = -31.4159266930206$$
$$x_{52} = -26.7035375555132$$
$$x_{53} = 26.7035375555132$$
$$x_{54} = 23.5619449019235$$
$$x_{55} = -7.85398163397448$$
$$x_{56} = -76.9690200129499$$
$$x_{57} = -56.5486675907774$$
$$x_{58} = 45.553093477052$$
$$x_{59} = 20.4203522483337$$
$$x_{60} = -37.6991118770355$$
$$x_{61} = -94.2477794613449$$
$$x_{62} = 100.530964774136$$
$$x_{63} = -67.5442420521806$$
$$x_{64} = -25.1327413641924$$
$$x_{65} = 73.8274273593601$$
$$x_{66} = -87.964594358935$$
$$x_{67} = 56.5486676180351$$
$$x_{68} = 17.2787595947439$$
$$x_{69} = -10.9955742875643$$
$$x_{70} = -95.8185759344887$$
$$x_{71} = 42.4115008234622$$
$$x_{72} = 95.8185759344887$$
$$x_{73} = 29.845130209103$$
$$x_{74} = -73.8274273593601$$
$$x_{75} = 48.6946861306418$$
$$x_{76} = 70.6858347057703$$
$$x_{77} = 83.2522053201295$$
$$x_{78} = -89.5353906273091$$
$$x_{79} = 50.2654824463558$$
$$x_{80} = 32.9867228626928$$
$$x_{81} = -81.6814090377756$$
$$x_{82} = -32.9867228626928$$
$$x_{83} = -45.553093477052$$
$$x_{84} = -1.5707963267949$$
$$x_{85} = -70.6858347057703$$
$$x_{86} = 37.6991120060109$$
$$x_{87} = -83.2522053201295$$
$$x_{88} = -86.3937979737193$$
$$x_{89} = 98.9601685880785$$
$$x_{90} = 94.2477796093526$$
$$x_{91} = 87.9645943356049$$
$$x_{92} = 92.6769832808989$$
$$x_{93} = 54.9778714378214$$
$$x_{94} = -12.5663704469816$$
$$x_{95} = 1.5707963267949$$
$$x_{96} = 31.4159266948554$$
$$x_{97} = 81.6814091609407$$