El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$1 - \cos{\left(2 x - \frac{4 \pi}{3} \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = - \frac{\pi}{3}$$
$$x_{2} = \frac{2 \pi}{3}$$
Solución numérica$$x_{1} = 46.0766919422696$$
$$x_{2} = -16.7551609176826$$
$$x_{3} = 86.9173966133072$$
$$x_{4} = -23.0383461173403$$
$$x_{5} = -67.0206435259362$$
$$x_{6} = 8.3775803324504$$
$$x_{7} = -98.4365695918018$$
$$x_{8} = 52.3598774920595$$
$$x_{9} = 5.23598800666376$$
$$x_{10} = 42.935099529436$$
$$x_{11} = -13.6135682472487$$
$$x_{12} = 64.9262479247718$$
$$x_{13} = 93.2005818993975$$
$$x_{14} = -89.0117921005483$$
$$x_{15} = -32.4631238594882$$
$$x_{16} = 20.943950773996$$
$$x_{17} = -63.8790502287$$
$$x_{18} = 1208.46597400842$$
$$x_{19} = 5.23598764360493$$
$$x_{20} = -92.1533843948345$$
$$x_{21} = -76.445421014295$$
$$x_{22} = -89.0117917833873$$
$$x_{23} = -79.5870139859625$$
$$x_{24} = -45.0294949511693$$
$$x_{25} = -10.4719758657697$$
$$x_{26} = -85.8701990270923$$
$$x_{27} = -10.4719752821901$$
$$x_{28} = -23.0383463762544$$
$$x_{29} = -16.7551605671492$$
$$x_{30} = 90.0589892610266$$
$$x_{31} = 11.5191732950364$$
$$x_{32} = -35.6047168268821$$
$$x_{33} = 20.9439509830371$$
$$x_{34} = 55.5014704492705$$
$$x_{35} = -38.7463091411329$$
$$x_{36} = -82.7286062895824$$
$$x_{37} = 64.9262480729538$$
$$x_{38} = 27.2271362060587$$
$$x_{39} = 42.9350993493207$$
$$x_{40} = 39.793507081887$$
$$x_{41} = 68.0678406238317$$
$$x_{42} = 71.2094337269916$$
$$x_{43} = 27.2271365802977$$
$$x_{44} = 17.8023585026368$$
$$x_{45} = -82.7286065932636$$
$$x_{46} = -19.8967533997196$$
$$x_{47} = 77.4926190262757$$
$$x_{48} = 83.7758042401686$$
$$x_{49} = -41.8879016078273$$
$$x_{50} = -95.2949773686894$$
$$x_{51} = -57.5958654064525$$
$$x_{52} = -70.1622358151638$$
$$x_{53} = -38.746309477683$$
$$x_{54} = -26.1799386560962$$
$$x_{55} = -45.0294946708353$$
$$x_{56} = 42.9350993385418$$
$$x_{57} = 58.6430626766196$$
$$x_{58} = 24.0855443607728$$
$$x_{59} = -19.8967526891948$$
$$x_{60} = -29.3215316353504$$
$$x_{61} = -51.3126802131926$$
$$x_{62} = -48.1710872355861$$
$$x_{63} = 30.3687289122185$$
$$x_{64} = -1.04719756597236$$
$$x_{65} = -1.04719780119744$$
$$x_{66} = -4.18879007668989$$
$$x_{67} = -60.7374577152796$$
$$x_{68} = 93.2005823000309$$
$$x_{69} = 14.6607655205163$$
$$x_{70} = -73.3038287909726$$
$$x_{71} = 80.6342112547578$$
$$x_{72} = 99.4837676032046$$
$$x_{73} = -60.7374580362607$$
$$x_{74} = 36.6519140985388$$
$$x_{75} = -54.4542724368569$$
$$x_{76} = 74.3510260719779$$
$$x_{77} = 96.342174651979$$
$$x_{78} = 33.5103218721904$$
$$x_{79} = 11.5191730025415$$
$$x_{80} = 71.2094333340459$$
$$x_{81} = 33.5103212825345$$
$$x_{82} = 86.9173965003448$$
$$x_{83} = 61.7846556610635$$
$$x_{84} = 49.2182851537437$$
$$x_{85} = -7.33038305744713$$
$$x_{86} = 49.2182847695711$$
$$x_{87} = -67.0206432262474$$