El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$5 \sin{\left(3 x \right)} - 12 \cos{\left(3 x \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = \frac{\operatorname{atan}{\left(\frac{12}{5} \right)}}{3}$$
Solución numérica$$x_{1} = -87.5725925648158$$
$$x_{2} = 16.0999650036473$$
$$x_{3} = -25.7879370442166$$
$$x_{4} = 84.1678058314262$$
$$x_{5} = -19.504751737037$$
$$x_{6} = 29.7135331692031$$
$$x_{7} = -65.5814439896873$$
$$x_{8} = -100.138963179175$$
$$x_{9} = 46.4686939883487$$
$$x_{10} = -73.9590243992601$$
$$x_{11} = -45.6846905169519$$
$$x_{12} = 90.4509911386058$$
$$x_{13} = -17.4103566346438$$
$$x_{14} = 33.9023233739895$$
$$x_{15} = -56.1566660289179$$
$$x_{16} = -78.1478146040465$$
$$x_{17} = 86.2622009338194$$
$$x_{18} = -48.8262831705417$$
$$x_{19} = -1.70239336669482$$
$$x_{20} = -36.2599125561825$$
$$x_{21} = 14.0055699012541$$
$$x_{22} = 22.3831503108269$$
$$x_{23} = 62.1766572562976$$
$$x_{24} = -54.0622709265247$$
$$x_{25} = 5.62798949168137$$
$$x_{26} = 89.4037935874092$$
$$x_{27} = 53.7990768467249$$
$$x_{28} = -32.0711223513961$$
$$x_{29} = -5.89118357148121$$
$$x_{30} = 77.8846205242466$$
$$x_{31} = -3.79678846908801$$
$$x_{32} = 66.365447461084$$
$$x_{33} = -76.0534195016533$$
$$x_{34} = -2310.77299375519$$
$$x_{35} = -95.9501729743886$$
$$x_{36} = -7.9855786738744$$
$$x_{37} = 105.111756855358$$
$$x_{38} = 75.7902254218534$$
$$x_{39} = 79.9790156266398$$
$$x_{40} = 99.8757690993752$$
$$x_{41} = 51.7046817443317$$
$$x_{42} = -63.4870488872941$$
$$x_{43} = 73.6958303194602$$
$$x_{44} = -59.2982586825077$$
$$x_{45} = 42.2799037835623$$
$$x_{46} = -98.0445680767818$$
$$x_{47} = 0.392001735698378$$
$$x_{48} = -41.4959003121655$$
$$x_{49} = -93.8557778719954$$
$$x_{50} = -112.705333793534$$
$$x_{51} = 27.6191380668099$$
$$x_{52} = -80.2422097064397$$
$$x_{53} = -21.5991468394302$$
$$x_{54} = 88.3565960362126$$
$$x_{55} = 9.81677969646776$$
$$x_{56} = -71.8646292968669$$
$$x_{57} = 57.9878670515113$$
$$x_{58} = 70.5542376658704$$
$$x_{59} = -34.1655174537893$$
$$x_{60} = 2.48639683809157$$
$$x_{61} = 97.781373996982$$
$$x_{62} = -23.6935419418234$$
$$x_{63} = -12.1743688786608$$
$$x_{64} = -91.7613827696022$$
$$x_{65} = -47.7790856193451$$
$$x_{66} = 64.2710523586908$$
$$x_{67} = 7.72238459407456$$
$$x_{68} = -82.3366048088328$$
$$x_{69} = -29.976727249003$$
$$x_{70} = -49.8734807217383$$
$$x_{71} = 11.911174798861$$
$$x_{72} = 60.0822621539045$$
$$x_{73} = -85.4781974624226$$
$$x_{74} = -67.6758390920805$$
$$x_{75} = -51.9678758241315$$
$$x_{76} = 82.073410729033$$
$$x_{77} = -58.2510611313111$$
$$x_{78} = 44.3742988859555$$
$$x_{79} = 35.9967184763827$$
$$x_{80} = -69.7702341944737$$
$$x_{81} = 20.2887552084337$$
$$x_{82} = 68.4598425634772$$
$$x_{83} = 40.1855086811691$$
$$x_{84} = 18.1943601060405$$
$$x_{85} = -44.6374929657553$$
$$x_{86} = 92.545386240999$$
$$x_{87} = 31.8079282715963$$
$$x_{88} = 24.4775454132201$$
$$x_{89} = -10.0799737762676$$
$$x_{90} = -14.268763981054$$
$$x_{91} = -43.5902954145587$$
$$x_{92} = -89.666987667209$$
$$x_{93} = 38.0911135787759$$
$$x_{94} = 55.8934719491181$$
$$x_{95} = -27.8823321466098$$