Graph of the function intersects the axis X at f = 0
so we need to solve the equation:
$$3 \sin{\left(x + \frac{\pi}{6} \right)} + 1 = 0$$
Solve this equationThe points of intersection with the axis X:
Analytical solution$$x_{1} = - \frac{\pi}{6} - \operatorname{asin}{\left(\frac{1}{3} \right)}$$
$$x_{2} = \operatorname{asin}{\left(\frac{1}{3} \right)} + \frac{5 \pi}{6}$$
Numerical solution$$x_{1} = 55.6852320795639$$
$$x_{2} = 5.41974962212717$$
$$x_{3} = 59.5064985520619$$
$$x_{4} = -97.5731341274278$$
$$x_{5} = -51.1289181424891$$
$$x_{6} = -0.863435685052421$$
$$x_{7} = 99.667529229821$$
$$x_{8} = -25.9961769137708$$
$$x_{9} = 93.3843439226414$$
$$x_{10} = -95.1112152927462$$
$$x_{11} = -85.0067635130686$$
$$x_{12} = 2.95783078744562$$
$$x_{13} = 24.2693055436659$$
$$x_{14} = -88.8280299855666$$
$$x_{15} = -91.2899488202482$$
$$x_{16} = 36.8356761580251$$
$$x_{17} = -3.32535451973397$$
$$x_{18} = 97.2056103951394$$
$$x_{19} = 15.5242014018048$$
$$x_{20} = 68.251602693923$$
$$x_{21} = 28.090572016164$$
$$x_{22} = -13.4298062994116$$
$$x_{23} = 17.9861202364863$$
$$x_{24} = 80.8179733082822$$
$$x_{25} = 46.9401279377027$$
$$x_{26} = -53.5908369771707$$
$$x_{27} = 49.4020467723843$$
$$x_{28} = 30.5524908508455$$
$$x_{29} = 61.9684173867434$$
$$x_{30} = 78.3560544736007$$
$$x_{31} = -38.5625475281299$$
$$x_{32} = -82.5448446783871$$
$$x_{33} = -28.4580957484523$$
$$x_{34} = -32.2793622209504$$
$$x_{35} = -47.3076516699911$$
$$x_{36} = 11.7029349293068$$
$$x_{37} = -22.1749104412727$$
$$x_{38} = -44.8457328353095$$
$$x_{39} = 87.1011586154618$$
$$x_{40} = 53.2233132448823$$
$$x_{41} = -63.6952887568483$$
$$x_{42} = 43.1188614652047$$
$$x_{43} = 9.2410160946252$$
$$x_{44} = 65.7896838592415$$
$$x_{45} = 84.6392397807802$$
$$x_{46} = -7.14662099223201$$
$$x_{47} = -41.0244663628115$$
$$x_{48} = 34.3737573233435$$
$$x_{49} = 90.9224250879598$$
$$x_{50} = -9.60853982691356$$
$$x_{51} = 74.5347880011026$$
$$x_{52} = -66.1572075915298$$
$$x_{53} = 21.8073867089844$$
$$x_{54} = -78.723578205889$$
$$x_{55} = 72.0728691664211$$
$$x_{56} = -147.838616584864$$
$$x_{57} = -69.9784740640279$$
$$x_{58} = -59.8740222843502$$
$$x_{59} = 40.6569426305231$$
$$x_{60} = -72.4403928987094$$
$$x_{61} = -76.2616593712075$$
$$x_{62} = -57.4121034496687$$
$$x_{63} = -19.7129916065912$$
$$x_{64} = -34.7412810556319$$
$$x_{65} = -15.8917251340931$$