El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$\sin{\left(3 x + \frac{\pi}{3} \right)} + 1 = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = - \frac{5 \pi}{18}$$
$$x_{2} = \frac{7 \pi}{18}$$
Solución numérica$$x_{1} = 15.8824962813824$$
$$x_{2} = -69.9877030211599$$
$$x_{3} = -28.0998008785227$$
$$x_{4} = -86.7428642451346$$
$$x_{5} = 55.6760032987458$$
$$x_{6} = -19.7222205668814$$
$$x_{7} = 68.24237375876$$
$$x_{8} = -30.1941959366071$$
$$x_{9} = -34.3829860965224$$
$$x_{10} = 66.1479787777296$$
$$x_{11} = 49.3928179190077$$
$$x_{12} = 24.2600765954214$$
$$x_{13} = -59.5157276137974$$
$$x_{14} = -76.2708881640826$$
$$x_{15} = -38.5717762514735$$
$$x_{16} = 72.4311638578408$$
$$x_{17} = 22.1656815906139$$
$$x_{18} = 80.808744235512$$
$$x_{19} = -26.0054058484444$$
$$x_{20} = 59.8647934405955$$
$$x_{21} = -55.3269374502927$$
$$x_{22} = -72.0820980392391$$
$$x_{23} = -57.4213325394611$$
$$x_{24} = 93.3751150431847$$
$$x_{25} = 11.6937061449814$$
$$x_{26} = -51.138147164715$$
$$x_{27} = 20.0712861640354$$
$$x_{28} = -15.5334304569628$$
$$x_{29} = 3.31612547660458$$
$$x_{30} = 47.2984225390473$$
$$x_{31} = -84.6484687079856$$
$$x_{32} = 28.4488667002524$$
$$x_{33} = -95.120444287049$$
$$x_{34} = 17.9768913197771$$
$$x_{35} = -49.0437517633446$$
$$x_{36} = 5.41052078886955$$
$$x_{37} = -80.4596783505706$$
$$x_{38} = 97.5639053549045$$
$$x_{39} = -82.5540734837771$$
$$x_{40} = 64.0535834321834$$
$$x_{41} = 32.637656853052$$
$$x_{42} = -9.25024519131613$$
$$x_{43} = 61.9591884851797$$
$$x_{44} = 7.50491594339682$$
$$x_{45} = -74.1764930939651$$
$$x_{46} = 30.543261770101$$
$$x_{47} = 38.920842341877$$
$$x_{48} = -13.4390353849187$$
$$x_{49} = -5.06145470762809$$
$$x_{50} = 34.7320519555797$$
$$x_{51} = 3.31612609210568$$
$$x_{52} = -97.2148394803031$$
$$x_{53} = -46.9493571911488$$
$$x_{54} = 82.9031394677449$$
$$x_{55} = 76.6199540057474$$
$$x_{56} = -53.2325423367113$$
$$x_{57} = -11.3446402989838$$
$$x_{58} = 53.5816082051786$$
$$x_{59} = -65.7989127573927$$
$$x_{60} = 74.5255589255718$$
$$x_{61} = -61.6101226767856$$
$$x_{62} = 91.280719578531$$
$$x_{63} = -32.2885910093003$$
$$x_{64} = -7.15585003585318$$
$$x_{65} = 99.6583004519716$$
$$x_{66} = -78.3652832483785$$
$$x_{67} = -17.6278255179502$$
$$x_{68} = -63.7045177283788$$
$$x_{69} = 36.8264470979358$$
$$x_{70} = 51.4872130884499$$
$$x_{71} = 26.3544716412833$$
$$x_{72} = 78.7143491037453$$
$$x_{73} = -38.5717763457435$$
$$x_{74} = -111.875605149508$$
$$x_{75} = -40.6661716073838$$
$$x_{76} = 84.9975349569597$$
$$x_{77} = 70.3367688009418$$
$$x_{78} = 43.1096329349692$$
$$x_{79} = 57.7703983766449$$
$$x_{80} = 95.4695102318843$$
$$x_{81} = -99.3092346007921$$
$$x_{82} = -36.4773812030096$$
$$x_{83} = 13.7881012202592$$
$$x_{84} = 9.59931105468093$$
$$x_{85} = 38.9208423710609$$
$$x_{86} = -21.8166155863094$$
$$x_{87} = -93.0260487973651$$