El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$2 - 3 \cos{\left(2 x + \frac{\pi}{4} \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = - \frac{\pi}{8} + \frac{\operatorname{acos}{\left(\frac{2}{3} \right)}}{2}$$
$$x_{2} = - \frac{\operatorname{acos}{\left(\frac{2}{3} \right)}}{2} + \frac{7 \pi}{8}$$
Solución numérica$$x_{1} = 14.8947298509663$$
$$x_{2} = 52.5938416940438$$
$$x_{3} = -76.2114571031377$$
$$x_{4} = -78.5119810861596$$
$$x_{5} = 94.275614861279$$
$$x_{6} = -29.0875672992908$$
$$x_{7} = 2.3283592366071$$
$$x_{8} = 30.6026931189152$$
$$x_{9} = 9.45261321435462$$
$$x_{10} = -19.6627893385214$$
$$x_{11} = 18.877391175124$$
$$x_{12} = 40.0274710796846$$
$$x_{13} = -6.25535005359435$$
$$x_{14} = -43.9544618966719$$
$$x_{15} = -10.2380113777521$$
$$x_{16} = -37.6712765894923$$
$$x_{17} = -13.3796040313419$$
$$x_{18} = 31.4437617894832$$
$$x_{19} = 53.4349103646117$$
$$x_{20} = 18.0363225045561$$
$$x_{21} = 62.8596883253811$$
$$x_{22} = 84.0097682299417$$
$$x_{23} = 44.0101324038423$$
$$x_{24} = -72.22879577898$$
$$x_{25} = -18.8217206679535$$
$$x_{26} = -81.6535737397494$$
$$x_{27} = -95.0610130246765$$
$$x_{28} = -87.936759046929$$
$$x_{29} = 28.3021691358934$$
$$x_{30} = -63.6450864887786$$
$$x_{31} = -57.361901181599$$
$$x_{32} = 87.9924295540994$$
$$x_{33} = 81.7092442469199$$
$$x_{34} = 71.4433976155826$$
$$x_{35} = -59.6624251646208$$
$$x_{36} = -69.9282717959581$$
$$x_{37} = -94.2199443541086$$
$$x_{38} = -32.2291599528806$$
$$x_{39} = 96.5761388443009$$
$$x_{40} = -91.9194203710867$$
$$x_{41} = 0.027835253585241$$
$$x_{42} = 46.3106563868642$$
$$x_{43} = 97.4172075148688$$
$$x_{44} = 22.0189838287138$$
$$x_{45} = -47.9371232208296$$
$$x_{46} = -85.6362350639071$$
$$x_{47} = -54.2203085280092$$
$$x_{48} = -25.945974645701$$
$$x_{49} = -28.2464986287229$$
$$x_{50} = 66.0012809789709$$
$$x_{51} = 68.3018049619928$$
$$x_{52} = 15.7357985215342$$
$$x_{53} = 552.107073614821$$
$$x_{54} = -41.65393791365$$
$$x_{55} = -82.4946424103173$$
$$x_{56} = 37.7269470966628$$
$$x_{57} = -98.2026056782663$$
$$x_{58} = -50.2376472038515$$
$$x_{59} = -35.3707526064704$$
$$x_{60} = -34.5296839359025$$
$$x_{61} = 72.2844662861505$$
$$x_{62} = 24.3195078117357$$
$$x_{63} = -15.6801280143637$$
$$x_{64} = -73.0698644495479$$
$$x_{65} = 36.8858784260948$$
$$x_{66} = 11.7531371973765$$
$$x_{67} = 33.744285772505$$
$$x_{68} = 74.5849902691724$$
$$x_{69} = -772.803957529504$$
$$x_{70} = 62.0186196548132$$
$$x_{71} = -100.503129661288$$
$$x_{72} = -51.0787158744194$$
$$x_{73} = 8.61154454378669$$
$$x_{74} = -79.3530497567275$$
$$x_{75} = 90.2929535371213$$
$$x_{76} = -3.95482607057248$$
$$x_{77} = 58.8770270012234$$
$$x_{78} = 75.4260589397403$$
$$x_{79} = -56.520832511031$$
$$x_{80} = 80.8681755763519$$
$$x_{81} = 6.31102056076483$$
$$x_{82} = -21.9633133215433$$
$$x_{83} = -7.09641872416228$$
$$x_{84} = 77.7265829227621$$
$$x_{85} = -12.5385353607739$$
$$x_{86} = -65.9456104718004$$
$$x_{87} = 50.2933177110219$$
$$x_{88} = 59.7180956717913$$