El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$\left(- 8 \sin{\left(x \right)} + 6 \cos{\left(x \right)}\right) + 9 = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = 2 \operatorname{atan}{\left(\frac{8}{3} - \frac{\sqrt{19}}{3} \right)}$$
$$x_{2} = 2 \operatorname{atan}{\left(\frac{\sqrt{19}}{3} + \frac{8}{3} \right)}$$
Solución numérica$$x_{1} = 52.0287530812286$$
$$x_{2} = -66.449714131591$$
$$x_{3} = 8.0464559309715$$
$$x_{4} = -42.2190265264652$$
$$x_{5} = 64.5951236955878$$
$$x_{6} = 65.4971773191803$$
$$x_{7} = -41.3169729028727$$
$$x_{8} = -79.0160847459502$$
$$x_{9} = -3.61786105979514$$
$$x_{10} = 45.745567774049$$
$$x_{11} = -53.8833435172318$$
$$x_{12} = -61.0685824480039$$
$$x_{13} = -22.4674169813339$$
$$x_{14} = -86.2013236767223$$
$$x_{15} = -98.7676942910815$$
$$x_{16} = 89.7278649243061$$
$$x_{17} = -72.7328994387706$$
$$x_{18} = 83.4446796171265$$
$$x_{19} = 20.6128265453307$$
$$x_{20} = 46.6476213976416$$
$$x_{21} = -92.4845089839019$$
$$x_{22} = -35.0337875956931$$
$$x_{23} = -67.3517677551835$$
$$x_{24} = -79.9181383695427$$
$$x_{25} = 33.1791971596898$$
$$x_{26} = -91.5824553603094$$
$$x_{27} = 103.196289162258$$
$$x_{28} = -47.6001582100522$$
$$x_{29} = 27.7980654761028$$
$$x_{30} = -23.3694706049264$$
$$x_{31} = 77.161494309947$$
$$x_{32} = 26.8960118525103$$
$$x_{33} = -17.0862852977468$$
$$x_{34} = -29.652655912106$$
$$x_{35} = -262.130512277751$$
$$x_{36} = 58.3119383884082$$
$$x_{37} = -54.7853971408244$$
$$x_{38} = 14.3296412381511$$
$$x_{39} = -9.90104636697473$$
$$x_{40} = 71.7803626263599$$
$$x_{41} = 52.9308067048211$$
$$x_{42} = 84.3467332407191$$
$$x_{43} = 34.0812507832824$$
$$x_{44} = 70.8783090027674$$
$$x_{45} = 40.364436090462$$
$$x_{46} = -97.8656406674889$$
$$x_{47} = 96.0110502314857$$
$$x_{48} = 21.5148801689232$$
$$x_{49} = -60.1665288244114$$
$$x_{50} = -28.7506022885135$$
$$x_{51} = 1.76327062379192$$
$$x_{52} = -16.1842316741543$$
$$x_{53} = 59.2139920120007$$
$$x_{54} = 8.94850955456403$$
$$x_{55} = -73.6349530623631$$
$$x_{56} = 273414.571912543$$
$$x_{57} = 39.4623824668694$$
$$x_{58} = 15.2316948617436$$
$$x_{59} = 78.0635479335395$$
$$x_{60} = -10.8030999905673$$
$$x_{61} = -4.51991468338767$$
$$x_{62} = 2.66532424738444$$
$$x_{63} = -35.9358412192856$$
$$x_{64} = 96.9131038550782$$
$$x_{65} = -48.5022118336448$$
$$x_{66} = -85.2992700531298$$
$$x_{67} = 90.6299185478987$$