El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$\frac{3 \sin^{2}{\left(x \right)} - 2 \sin{\left(x \right)}}{\cos{\left(x \right)}} - 1 = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = - 2 \operatorname{atan}{\left(-1 + \frac{\sqrt{-8 - 2 \sqrt[3]{\frac{\sqrt{1887}}{9} + 6} - \frac{14}{3 \sqrt[3]{\frac{\sqrt{1887}}{9} + 6}} + \frac{24}{\sqrt{-4 + \frac{14}{3 \sqrt[3]{\frac{\sqrt{1887}}{9} + 6}} + 2 \sqrt[3]{\frac{\sqrt{1887}}{9} + 6}}}}}{2} + \frac{\sqrt{-4 + \frac{14}{3 \sqrt[3]{\frac{\sqrt{1887}}{9} + 6}} + 2 \sqrt[3]{\frac{\sqrt{1887}}{9} + 6}}}{2} \right)}$$
$$x_{2} = 2 \operatorname{atan}{\left(- \frac{\sqrt{-4 + \frac{14}{3 \sqrt[3]{\frac{\sqrt{1887}}{9} + 6}} + 2 \sqrt[3]{\frac{\sqrt{1887}}{9} + 6}}}{2} + \frac{\sqrt{-8 - 2 \sqrt[3]{\frac{\sqrt{1887}}{9} + 6} - \frac{14}{3 \sqrt[3]{\frac{\sqrt{1887}}{9} + 6}} + \frac{24}{\sqrt{-4 + \frac{14}{3 \sqrt[3]{\frac{\sqrt{1887}}{9} + 6}} + 2 \sqrt[3]{\frac{\sqrt{1887}}{9} + 6}}}}}{2} + 1 \right)}$$
Solución numérica$$x_{1} = -0.325783414376278$$
$$x_{2} = 81.3556255789584$$
$$x_{3} = -25.4585246430946$$
$$x_{4} = -61.7919318126126$$
$$x_{5} = 76.4381449453383$$
$$x_{6} = -107.139933636429$$
$$x_{7} = 145.553183324314$$
$$x_{8} = 43.6565137358808$$
$$x_{9} = -31.7417099502742$$
$$x_{10} = -74.3583024269717$$
$$x_{11} = 70.1549596381587$$
$$x_{12} = 63.8717743309792$$
$$x_{13} = 26.1726624879016$$
$$x_{14} = -11.5264493551759$$
$$x_{15} = -69.4408217933517$$
$$x_{16} = 18.5237725071625$$
$$x_{17} = -24.0928199695351$$
$$x_{18} = -36.6591905838942$$
$$x_{19} = 32.4558477950812$$
$$x_{20} = -17.8096346623555$$
$$x_{21} = -55.508746505433$$
$$x_{22} = 75.0724402717788$$
$$x_{23} = 19.8894771807221$$
$$x_{24} = 57.5885890237996$$
$$x_{25} = -38.0248952574538$$
$$x_{26} = 37.3733284287012$$
$$x_{27} = -119.706304250788$$
$$x_{28} = -63.1576364861721$$
$$x_{29} = -30.3760052767146$$
$$x_{30} = -99.4910436556901$$
$$x_{31} = -19.175339335915$$
$$x_{32} = 87.6388108861379$$
$$x_{33} = 49.9396990430604$$
$$x_{34} = -44.3080805646334$$
$$x_{35} = 24.8069578143421$$
$$x_{36} = 5.95740189280331$$
$$x_{37} = 95.2877008668771$$
$$x_{38} = -68.0751171197922$$
$$x_{39} = 56.22288435024$$
$$x_{40} = -873.688541112339$$
$$x_{41} = -6.60896872155586$$
$$x_{42} = 93.9219961933175$$
$$x_{43} = -12.8921540287355$$
$$x_{44} = 12.2405871999829$$
$$x_{45} = -75.7240071005313$$
$$x_{46} = 82.7213302525179$$
$$x_{47} = 31.0901431215217$$
$$x_{48} = 68.7892549645992$$
$$x_{49} = 100.205181500497$$
$$x_{50} = -82.0071924077109$$
$$x_{51} = -50.591265871813$$
$$x_{52} = 62.5060696574196$$
$$x_{53} = -56.8744511789926$$
$$x_{54} = -88.2903777148905$$