El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$\left(\sqrt{2 \cos{\left(x \right)}}\right)^{6} - \sqrt{2} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = - \operatorname{acos}{\left(\frac{\sqrt[6]{2}}{2} \right)} + 2 \pi$$
$$x_{2} = \operatorname{acos}{\left(\frac{\sqrt[6]{2}}{2} \right)}$$
Solución numérica$$x_{1} = 51.2404063766274$$
$$x_{2} = -43.0073732310664$$
$$x_{3} = -13.5412945335499$$
$$x_{4} = 49.290558538246$$
$$x_{5} = 19.8244798407295$$
$$x_{6} = 112.122411610042$$
$$x_{7} = 17.8746320023481$$
$$x_{8} = 74.4232997669643$$
$$x_{9} = -63.8067769909866$$
$$x_{10} = 93.2728556885031$$
$$x_{11} = 43.0073732310664$$
$$x_{12} = 0.974923919190704$$
$$x_{13} = 13.5412945335499$$
$$x_{14} = -70.0899622981662$$
$$x_{15} = -44.9572210694478$$
$$x_{16} = 7.25810922637029$$
$$x_{17} = 11.5914466951685$$
$$x_{18} = -68.1401144597847$$
$$x_{19} = -76.3731476053457$$
$$x_{20} = 30.4410026167072$$
$$x_{21} = 26.107665147909$$
$$x_{22} = 68.1401144597847$$
$$x_{23} = 101.505888834064$$
$$x_{24} = -0.974923919190704$$
$$x_{25} = 32.3908504550886$$
$$x_{26} = 63.8067769909866$$
$$x_{27} = 99.5560409956827$$
$$x_{28} = 95.2227035268845$$
$$x_{29} = 38.6740357622682$$
$$x_{30} = 5.30826138798888$$
$$x_{31} = -55.5737438454256$$
$$x_{32} = -61.8569291526052$$
$$x_{33} = -86.9896703813235$$
$$x_{34} = -5.30826138798888$$
$$x_{35} = 55.5737438454256$$
$$x_{36} = 61.8569291526052$$
$$x_{37} = 583.361309648511$$
$$x_{38} = -36.7241879238868$$
$$x_{39} = -88.9395182197049$$
$$x_{40} = 82.6563329125253$$
$$x_{41} = -82.6563329125253$$
$$x_{42} = -32.3908504550886$$
$$x_{43} = 76.3731476053457$$
$$x_{44} = -49.290558538246$$
$$x_{45} = 86.9896703813235$$
$$x_{46} = -93.2728556885031$$
$$x_{47} = 44.9572210694478$$
$$x_{48} = 70.0899622981662$$
$$x_{49} = -99.5560409956827$$
$$x_{50} = -26.107665147909$$
$$x_{51} = -57.523591683807$$
$$x_{52} = -19.8244798407295$$
$$x_{53} = -38.6740357622682$$
$$x_{54} = 24.1578173095276$$
$$x_{55} = -80.7064850741439$$
$$x_{56} = -11.5914466951685$$
$$x_{57} = -24.1578173095276$$
$$x_{58} = -17.8746320023481$$