El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$\left|{2 \cos{\left(x \right)}}\right| - 1 = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = \frac{\pi}{3}$$
$$x_{2} = \frac{2 \pi}{3}$$
$$x_{3} = \frac{4 \pi}{3}$$
$$x_{4} = \frac{5 \pi}{3}$$
Solución numérica$$x_{1} = -4.18879020478639$$
$$x_{2} = 32.4631240870945$$
$$x_{3} = -42.9350995990605$$
$$x_{4} = -10.471975511966$$
$$x_{5} = -96.342174710087$$
$$x_{6} = 33.5103216382911$$
$$x_{7} = 82.7286065445312$$
$$x_{8} = 38.7463093942741$$
$$x_{9} = 39.7935069454707$$
$$x_{10} = 8.37758040957278$$
$$x_{11} = -46.0766922526503$$
$$x_{12} = 63.8790506229925$$
$$x_{13} = -76.4454212373516$$
$$x_{14} = -49.2182849062401$$
$$x_{15} = 41.8879020478639$$
$$x_{16} = 269.129770657526$$
$$x_{17} = -63.8790506229925$$
$$x_{18} = 48.1710873550435$$
$$x_{19} = -41.8879020478639$$
$$x_{20} = 30.3687289847013$$
$$x_{21} = -32.4631240870945$$
$$x_{22} = 17.8023583703422$$
$$x_{23} = -79.5870138909414$$
$$x_{24} = 77.4926187885482$$
$$x_{25} = -48.1710873550435$$
$$x_{26} = 85.870199198121$$
$$x_{27} = -19.8967534727354$$
$$x_{28} = 24.0855436775217$$
$$x_{29} = -13.6135681655558$$
$$x_{30} = 4.18879020478639$$
$$x_{31} = -5.23598775598299$$
$$x_{32} = -74.3510261349584$$
$$x_{33} = -92.1533845053006$$
$$x_{34} = -17.8023583703422$$
$$x_{35} = -2.0943951023932$$
$$x_{36} = 98.4365698124802$$
$$x_{37} = -54.4542726622231$$
$$x_{38} = 275.412955964705$$
$$x_{39} = -35.6047167406843$$
$$x_{40} = -98.4365698124802$$
$$x_{41} = 16.7551608191456$$
$$x_{42} = -24.0855436775217$$
$$x_{43} = 99.4837673636768$$
$$x_{44} = 54.4542726622231$$
$$x_{45} = 26.1799387799149$$
$$x_{46} = 10.471975511966$$
$$x_{47} = 19.8967534727354$$
$$x_{48} = 83.7758040957278$$
$$x_{49} = -26.1799387799149$$
$$x_{50} = 96.342174710087$$
$$x_{51} = -90.0589894029074$$
$$x_{52} = 60.7374579694027$$
$$x_{53} = -57.5958653158129$$
$$x_{54} = 3803.42150594604$$
$$x_{55} = -55.5014702134197$$
$$x_{56} = -52.3598775598299$$
$$x_{57} = -99.4837673636768$$
$$x_{58} = 61.7846555205993$$
$$x_{59} = -77.4926187885482$$
$$x_{60} = -70.162235930172$$
$$x_{61} = -61.7846555205993$$
$$x_{62} = 46.0766922526503$$
$$x_{63} = 11.5191730631626$$
$$x_{64} = -85.870199198121$$
$$x_{65} = 52.3598775598299$$
$$x_{66} = -60.7374579694027$$
$$x_{67} = -68.0678408277789$$
$$x_{68} = -33.5103216382911$$
$$x_{69} = 2.0943951023932$$
$$x_{70} = -30.3687289847013$$
$$x_{71} = -93.2005820564972$$
$$x_{72} = 90.0589894029074$$
$$x_{73} = -11.5191730631626$$
$$x_{74} = 76.4454212373516$$
$$x_{75} = 55.5014702134197$$
$$x_{76} = -83.7758040957278$$
$$x_{77} = 68.0678408277789$$
$$x_{78} = -27.2271363311115$$
$$x_{79} = -673.348025419412$$
$$x_{80} = 92.1533845053006$$
$$x_{81} = -39.7935069454707$$
$$x_{82} = 74.3510261349584$$
$$x_{83} = 70.162235930172$$
$$x_{84} = -71.2094334813686$$