El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$\cos{\left(\frac{x}{2} \right)} - 1 = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = 0$$
$$x_{2} = 4 \pi$$
Solución numérica$$x_{1} = -339.292004463459$$
$$x_{2} = -75.3982230244771$$
$$x_{3} = 37.699112034073$$
$$x_{4} = 87.9645943359415$$
$$x_{5} = -100.53096461474$$
$$x_{6} = 12.5663716216992$$
$$x_{7} = 87.9645951697672$$
$$x_{8} = 75.3982231443299$$
$$x_{9} = 75.3982242010893$$
$$x_{10} = 87.9645950596493$$
$$x_{11} = -12.5663711704395$$
$$x_{12} = 62.8318541035118$$
$$x_{13} = -12.5663702980387$$
$$x_{14} = 25.1327416777796$$
$$x_{15} = 12.5663701654734$$
$$x_{16} = 12.566371289085$$
$$x_{17} = -25.1327429452907$$
$$x_{18} = 75.3982234996238$$
$$x_{19} = -25.1327406696083$$
$$x_{20} = -62.8318526379222$$
$$x_{21} = 50.2654816836948$$
$$x_{22} = -12.5663716390742$$
$$x_{23} = -50.2654815299205$$
$$x_{24} = -50.2654831290744$$
$$x_{25} = -62.8318542584121$$
$$x_{26} = -50.2654829362526$$
$$x_{27} = -62.8318535180004$$
$$x_{28} = 25.1327407976605$$
$$x_{29} = -50.2654834520414$$
$$x_{30} = -12.5663696273954$$
$$x_{31} = 25.1327398318424$$
$$x_{32} = 37.6991123150382$$
$$x_{33} = 87.9645933670472$$
$$x_{34} = 0$$
$$x_{35} = -87.9645950762365$$
$$x_{36} = 12.5663696903306$$
$$x_{37} = 37.6991108423748$$
$$x_{38} = 25.1327402133162$$
$$x_{39} = -37.6991126992556$$
$$x_{40} = -62.831851347466$$
$$x_{41} = -62.8318520510992$$
$$x_{42} = 62.8318531970184$$
$$x_{43} = -87.9645934511713$$
$$x_{44} = -75.398224618165$$
$$x_{45} = -37.6991110758133$$
$$x_{46} = 50.2654824463372$$
$$x_{47} = 37.6991112800661$$
$$x_{48} = 75.3982240185352$$
$$x_{49} = -87.9645934903961$$
$$x_{50} = 100.530964414577$$
$$x_{51} = 62.8318527737309$$
$$x_{52} = -62.8318540899534$$
$$x_{53} = 50.2654816113039$$
$$x_{54} = -37.6991118772906$$
$$x_{55} = 25.1327427229237$$
$$x_{56} = 100.530963999089$$
$$x_{57} = 75.3982246787105$$
$$x_{58} = -50.265481935943$$
$$x_{59} = 100.530965273463$$
$$x_{60} = -113.097333611656$$
$$x_{61} = 75.3982226607454$$
$$x_{62} = 12.5663704404135$$
$$x_{63} = 50.2654833855111$$
$$x_{64} = -87.9645952061008$$
$$x_{65} = 50.2654832362872$$
$$x_{66} = -12.5663706941362$$
$$x_{67} = -25.1327409922366$$
$$x_{68} = 25.1327422523855$$
$$x_{69} = -75.3982226734831$$
$$x_{70} = -2450.4422691113$$
$$x_{71} = -25.1327401961945$$
$$x_{72} = -75.3982238771266$$
$$x_{73} = 100.530964758156$$
$$x_{74} = 62.8318520947719$$
$$x_{75} = 37.6991127786276$$
$$x_{76} = -75.3982240789539$$
$$x_{77} = 12.5663724644809$$
$$x_{78} = 37.6991111844838$$
$$x_{79} = -100.530963933814$$
$$x_{80} = -87.9645943585769$$
$$x_{81} = -25.1327415428233$$
$$x_{82} = 100.530964589585$$
$$x_{83} = -37.6991109019735$$
$$x_{84} = -37.6991125894353$$
$$x_{85} = -25.1327422115415$$
$$x_{86} = 87.964593548137$$
$$x_{87} = -50.2654822841315$$
$$x_{88} = -791.681347222187$$
$$x_{89} = -100.530964897478$$
$$x_{90} = 62.8318536450421$$