El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$5 \sin{\left(3 x \right)} + 4 \cos{\left(3 x \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = - \frac{\operatorname{atan}{\left(\frac{4}{5} \right)}}{3}$$
Solución numérica$$x_{1} = 89.8340757554996$$
$$x_{2} = -75.6231373335629$$
$$x_{3} = -97.6142859086914$$
$$x_{4} = 76.2205075899438$$
$$x_{5} = 58.4181492196016$$
$$x_{6} = 64.7013345267812$$
$$x_{7} = 14.4358520693445$$
$$x_{8} = -46.3016059000581$$
$$x_{9} = -59.9151740656139$$
$$x_{10} = 78.314902692337$$
$$x_{11} = -94.4726932551016$$
$$x_{12} = 69.9373222827642$$
$$x_{13} = -66.1983593727935$$
$$x_{14} = -90.2839030503153$$
$$x_{15} = -20.1216671201432$$
$$x_{16} = -7.55529650578404$$
$$x_{17} = 25.9550251325071$$
$$x_{18} = 45.8517786052425$$
$$x_{19} = -29.5464450809126$$
$$x_{20} = -13.8384818129636$$
$$x_{21} = -27.4520499785194$$
$$x_{22} = -40.0184205928786$$
$$x_{23} = -12.791284261767$$
$$x_{24} = -42.1128156952718$$
$$x_{25} = -9692.03824997192$$
$$x_{26} = -68.2927544751867$$
$$x_{27} = -9.64969160817723$$
$$x_{28} = -57.8207789632207$$
$$x_{29} = -88.1895079479221$$
$$x_{30} = 16.5302471717377$$
$$x_{31} = -0.224913647407851$$
$$x_{32} = -22.2160622225364$$
$$x_{33} = -95.5198908062982$$
$$x_{34} = 34.3326055420799$$
$$x_{35} = 36.4270006444731$$
$$x_{36} = 52.134963912422$$
$$x_{37} = -73.5287422311697$$
$$x_{38} = -11.7440867105704$$
$$x_{39} = -79.8119275383493$$
$$x_{40} = -35.8296303880922$$
$$x_{41} = -81.9063226407425$$
$$x_{42} = 47.9461737076356$$
$$x_{43} = 100.306051267466$$
$$x_{44} = 30.1438153372935$$
$$x_{45} = 94.0228659602859$$
$$x_{46} = 80.4092977947302$$
$$x_{47} = 3.96387655737854$$
$$x_{48} = 67.842927180371$$
$$x_{49} = -86.0951128455289$$
$$x_{50} = 32.2382104396867$$
$$x_{51} = 6.05827165977174$$
$$x_{52} = 8.15266676216493$$
$$x_{53} = 96.1172610626791$$
$$x_{54} = -92.3782981527085$$
$$x_{55} = 28.0494202349003$$
$$x_{56} = -53.6319887584343$$
$$x_{57} = 65.7485320779778$$
$$x_{58} = -3.36650630099764$$
$$x_{59} = 38.5213957468663$$
$$x_{60} = 91.9284708578927$$
$$x_{61} = 1.86948145498534$$
$$x_{62} = 56.3237541172084$$
$$x_{63} = 43.7573835028493$$
$$x_{64} = 54.2293590148152$$
$$x_{65} = -62.0095691680071$$
$$x_{66} = 41.6629884004561$$
$$x_{67} = 98.2116561650723$$
$$x_{68} = 82.5036928971234$$
$$x_{69} = 72.0317173851574$$
$$x_{70} = -5.46090140339084$$
$$x_{71} = -24.3104573249296$$
$$x_{72} = -84.0007177431357$$
$$x_{73} = 21.7662349277207$$
$$x_{74} = -77.7175324359561$$
$$x_{75} = -51.5375936560411$$
$$x_{76} = 12.3414569669513$$
$$x_{77} = -55.7263838608275$$
$$x_{78} = 23.8606300301139$$
$$x_{79} = 10.2470618645581$$
$$x_{80} = -15.9328769153568$$
$$x_{81} = -74.5759397823663$$
$$x_{82} = 18.6246422741309$$
$$x_{83} = 224.922559859861$$
$$x_{84} = -64.1039642704003$$
$$x_{85} = 74.1261124875506$$
$$x_{86} = -99.7086810110846$$
$$x_{87} = 87.7396806531064$$
$$x_{88} = -49.4431985536479$$
$$x_{89} = -44.207210797665$$
$$x_{90} = -31.6408401833058$$
$$x_{91} = -18.02727201775$$
$$x_{92} = -33.735235285699$$
$$x_{93} = -37.9240254904854$$
$$x_{94} = 50.0405688100288$$
$$x_{95} = 60.5125443219948$$