Graph of the function intersects the axis X at f = 0
so we need to solve the equation:
$$2 \cos{\left(x \right)} - \frac{1}{2} = 0$$
Solve this equationThe points of intersection with the axis X:
Analytical solution$$x_{1} = - \operatorname{acos}{\left(\frac{1}{4} \right)} + 2 \pi$$
$$x_{2} = \operatorname{acos}{\left(\frac{1}{4} \right)}$$
Numerical solution$$x_{1} = 99.2128488432206$$
$$x_{2} = 74.0801076145022$$
$$x_{3} = -74.0801076145022$$
$$x_{4} = -26.4508573003712$$
$$x_{5} = 4.96506923552677$$
$$x_{6} = 70.4331544506283$$
$$x_{7} = 86.6464782288614$$
$$x_{8} = 36.3809957714247$$
$$x_{9} = -70.4331544506283$$
$$x_{10} = 89.282710372167$$
$$x_{11} = -36.3809957714247$$
$$x_{12} = 1.31811607165282$$
$$x_{13} = -99.2128488432206$$
$$x_{14} = 23.8146251570655$$
$$x_{15} = 48.9473663857839$$
$$x_{16} = 26.4508573003712$$
$$x_{17} = -92.929663536041$$
$$x_{18} = -61.513737000143$$
$$x_{19} = 51.5835985290895$$
$$x_{20} = 55.2305516929635$$
$$x_{21} = -17.5314398498859$$
$$x_{22} = 42.6641810786043$$
$$x_{23} = -1421.31799549424$$
$$x_{24} = -32.7340426075507$$
$$x_{25} = 17.5314398498859$$
$$x_{26} = 76.7163397578079$$
$$x_{27} = -23.8146251570655$$
$$x_{28} = -57.8667838362691$$
$$x_{29} = -30.0978104642451$$
$$x_{30} = 32.7340426075507$$
$$x_{31} = -51.5835985290895$$
$$x_{32} = 92.929663536041$$
$$x_{33} = 30.0978104642451$$
$$x_{34} = 64.1499691434487$$
$$x_{35} = -64.1499691434487$$
$$x_{36} = 82.9995250649874$$
$$x_{37} = -1.31811607165282$$
$$x_{38} = 13.884486686012$$
$$x_{39} = 7.6013013788324$$
$$x_{40} = -42.6641810786043$$
$$x_{41} = 20.1676719931916$$
$$x_{42} = 67.7969223073226$$
$$x_{43} = -55.2305516929635$$
$$x_{44} = -67.7969223073226$$
$$x_{45} = -7.6013013788324$$
$$x_{46} = 80.3632929216818$$
$$x_{47} = -11.2482545427064$$
$$x_{48} = -39.0172279147303$$
$$x_{49} = 61.513737000143$$
$$x_{50} = -48.9473663857839$$
$$x_{51} = 45.3004132219099$$
$$x_{52} = -13.884486686012$$
$$x_{53} = -76.7163397578079$$
$$x_{54} = -45.3004132219099$$
$$x_{55} = 39.0172279147303$$
$$x_{56} = 57.8667838362691$$
$$x_{57} = -20.1676719931916$$
$$x_{58} = -189.81367528704$$
$$x_{59} = -80.3632929216818$$
$$x_{60} = -82.9995250649874$$
$$x_{61} = -95.5658956793466$$
$$x_{62} = 11.2482545427064$$
$$x_{63} = -86.6464782288614$$
$$x_{64} = -89.282710372167$$
$$x_{65} = 95.5658956793466$$
$$x_{66} = -4.96506923552677$$