El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$1 - \cos{\left(3 x \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = 0$$
$$x_{2} = \frac{2 \pi}{3}$$
Solución numérica$$x_{1} = 4.18879026156543$$
$$x_{2} = -50.2654823108466$$
$$x_{3} = -29.3215315957413$$
$$x_{4} = -41.8879015909008$$
$$x_{5} = -96.3421745469196$$
$$x_{6} = -73.3038287459741$$
$$x_{7} = -98.4365696440843$$
$$x_{8} = 8.37758033410453$$
$$x_{9} = 58.6430627071515$$
$$x_{10} = 56.5486676233132$$
$$x_{11} = 90.0589892608483$$
$$x_{12} = 37.6991113434848$$
$$x_{13} = -441575121.501282$$
$$x_{14} = -58.6430628407171$$
$$x_{15} = -71.2094336231345$$
$$x_{16} = -100.530964767287$$
$$x_{17} = 100.530964778649$$
$$x_{18} = -12.5663704869723$$
$$x_{19} = -46.0766921879046$$
$$x_{20} = 33.5103217994214$$
$$x_{21} = -54.4542724952377$$
$$x_{22} = 83.7758042295396$$
$$x_{23} = -85.8701992330716$$
$$x_{24} = -31.4159266859544$$
$$x_{25} = 87.9645943355056$$
$$x_{26} = 31.4159266487811$$
$$x_{27} = 81.6814091524463$$
$$x_{28} = -10.4719753473561$$
$$x_{29} = 39.7935070730078$$
$$x_{30} = -56.548667625889$$
$$x_{31} = -4.18879008400713$$
$$x_{32} = 85.8701992926441$$
$$x_{33} = 29.3215313536198$$
$$x_{34} = -69.115038422181$$
$$x_{35} = 12.5663704684363$$
$$x_{36} = -35.6047172724316$$
$$x_{37} = 98.4365698045197$$
$$x_{38} = 41.8879021332297$$
$$x_{39} = -77.4926189173344$$
$$x_{40} = -48.1710872415186$$
$$x_{41} = 75.3982237804204$$
$$x_{42} = -90.0589893499645$$
$$x_{43} = 54.4542725528033$$
$$x_{44} = -33.5103217610131$$
$$x_{45} = 16.7551606647126$$
$$x_{46} = -14.6607657359666$$
$$x_{47} = -2.09439502690814$$
$$x_{48} = 43.9822971693627$$
$$x_{49} = -83.7758040750549$$
$$x_{50} = 52.3598774932141$$
$$x_{51} = -16.755160961199$$
$$x_{52} = -92.1533843995496$$
$$x_{53} = 64.9262482454786$$
$$x_{54} = 35.6047169091797$$
$$x_{55} = 46.076691966571$$
$$x_{56} = 94.2477796093527$$
$$x_{57} = 833.569250843322$$
$$x_{58} = -81.6814090376256$$
$$x_{59} = 0$$
$$x_{60} = 14.6607655553299$$
$$x_{61} = 48.1710874363538$$
$$x_{62} = 20.943951173337$$
$$x_{63} = -79.5870139829524$$
$$x_{64} = -8.37758024222806$$
$$x_{65} = -43.9822971746469$$
$$x_{66} = -69.1150389029232$$
$$x_{67} = 77.4926189449124$$
$$x_{68} = 50.2654824463613$$
$$x_{69} = 79.5870140598991$$
$$x_{70} = 98.4365697102782$$
$$x_{71} = 6.28318528432449$$
$$x_{72} = -67.0206429069494$$
$$x_{73} = -75.3982238398266$$
$$x_{74} = 73.3038284231128$$
$$x_{75} = -39.7935069082666$$
$$x_{76} = -37.6991118769598$$
$$x_{77} = -6.28318515591421$$
$$x_{78} = -27.2271364801679$$
$$x_{79} = -25.1327413022544$$
$$x_{80} = -35.604716824613$$
$$x_{81} = 96.3421746527392$$
$$x_{82} = 62.8318529572331$$
$$x_{83} = 37.6991119985219$$
$$x_{84} = 10.4719753957034$$
$$x_{85} = -52.3598773942745$$
$$x_{86} = -23.0383458748855$$
$$x_{87} = -20.9439509761532$$
$$x_{88} = -60.7374583801782$$
$$x_{89} = -94.2477794662643$$
$$x_{90} = -87.964594359041$$
$$x_{91} = 60.7374578111775$$
$$x_{92} = 18.8495558248099$$
$$x_{93} = 161.26842260871$$
$$x_{94} = 92.1533846197794$$