Graph of the function intersects the axis X at f = 0
so we need to solve the equation:
$$\cos{\left(x \right)} - 1 = 0$$
Solve this equationThe points of intersection with the axis X:
Analytical solution$$x_{1} = 0$$
$$x_{2} = 2 \pi$$
Numerical solution$$x_{1} = 81.6814084860076$$
$$x_{2} = 18.8495564031971$$
$$x_{3} = 94.2477800892631$$
$$x_{4} = 6.28318579821791$$
$$x_{5} = 6.28318528420851$$
$$x_{6} = -6.2831851275477$$
$$x_{7} = 75.3982240031607$$
$$x_{8} = 37.6991115173992$$
$$x_{9} = -18.8495552124105$$
$$x_{10} = -75.3982238741744$$
$$x_{11} = -37.6991113479743$$
$$x_{12} = -31.4159267157965$$
$$x_{13} = -31.4159260208155$$
$$x_{14} = 75.3982232188727$$
$$x_{15} = 43.9822974733639$$
$$x_{16} = -50.2654829667315$$
$$x_{17} = -94.2477801171671$$
$$x_{18} = 37.6991120311338$$
$$x_{19} = 12.5663710110881$$
$$x_{20} = -87.9645943586158$$
$$x_{21} = 62.8318535568358$$
$$x_{22} = 37.6991113348642$$
$$x_{23} = -75.3982231720141$$
$$x_{24} = 100.530964759815$$
$$x_{25} = 56.5486668532011$$
$$x_{26} = -94.2477797298079$$
$$x_{27} = 100.530965157364$$
$$x_{28} = 0$$
$$x_{29} = 50.2654821322586$$
$$x_{30} = -81.6814090382277$$
$$x_{31} = -56.5486674685864$$
$$x_{32} = -6.2831858160515$$
$$x_{33} = -25.1327415297174$$
$$x_{34} = 87.9645946044253$$
$$x_{35} = 6.28318626747926$$
$$x_{36} = 50.2654829439723$$
$$x_{37} = 56.5486676011951$$
$$x_{38} = 69.1150379887504$$
$$x_{39} = -43.9822976246252$$
$$x_{40} = 12.5663711301703$$
$$x_{41} = 69.115038794053$$
$$x_{42} = -43.9822971745392$$
$$x_{43} = -69.1150379045123$$
$$x_{44} = 43.9822971694647$$
$$x_{45} = 6.28318500093652$$
$$x_{46} = 31.4159268459961$$
$$x_{47} = -87.964593928489$$
$$x_{48} = 18.8495556275525$$
$$x_{49} = -37.6991121287155$$
$$x_{50} = 25.1327416384075$$
$$x_{51} = -62.8318534787248$$
$$x_{52} = -56.5486682426592$$
$$x_{53} = -81.6814075578313$$
$$x_{54} = -12.5663710889626$$
$$x_{55} = -12.5663703112531$$
$$x_{56} = 87.964594335905$$
$$x_{57} = -62.831852673202$$
$$x_{58} = 50.2654824463392$$
$$x_{59} = -100.530964626003$$
$$x_{60} = -81.6814084945807$$
$$x_{61} = 81.6814085860518$$
$$x_{62} = 43.9822966661001$$
$$x_{63} = -43.9822967932182$$
$$x_{64} = -37.6991118772631$$
$$x_{65} = -18.8495555173448$$
$$x_{66} = 81.6814091897036$$
$$x_{67} = 94.2477792651059$$
$$x_{68} = -87.9645947692094$$
$$x_{69} = -50.2654822863493$$
$$x_{70} = 56.5486682809363$$
$$x_{71} = -81.6814092565354$$
$$x_{72} = -50.265482641087$$
$$x_{73} = -94.2477794452815$$
$$x_{74} = 31.4159260648825$$
$$x_{75} = -6.28318555849548$$
$$x_{76} = 87.9645938121814$$
$$x_{77} = 12.5663704426592$$
$$x_{78} = 56.5486680806249$$
$$x_{79} = -18.8495563230046$$
$$x_{80} = 62.8318527849002$$
$$x_{81} = -69.1150386869085$$
$$x_{82} = 25.1327408328211$$
$$x_{83} = 94.2477796093523$$
$$x_{84} = -75.3982231045728$$
$$x_{85} = -25.1327407505866$$
$$x_{86} = -31.4159260507536$$