El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$\sin{\left(3 x \right)} + \cos{\left(3 x \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = - \frac{\pi}{12}$$
Solución numérica$$x_{1} = -55.7632696012188$$
$$x_{2} = -64.1408500107916$$
$$x_{3} = 1.83259571459405$$
$$x_{4} = 50.0036830696375$$
$$x_{5} = 21.7293491873294$$
$$x_{6} = -11.7809724509617$$
$$x_{7} = -51.5744793964324$$
$$x_{8} = 25.9181393921158$$
$$x_{9} = -40.0553063332699$$
$$x_{10} = -29.5833308213039$$
$$x_{11} = -15.9697626557481$$
$$x_{12} = -427.518400276011$$
$$x_{13} = -49.4800842940392$$
$$x_{14} = 43.720497762458$$
$$x_{15} = 76.1836218495525$$
$$x_{16} = 69.9004365423729$$
$$x_{17} = 12.30457122656$$
$$x_{18} = 87.7027949127151$$
$$x_{19} = -88.2263936883134$$
$$x_{20} = -95.5567765466895$$
$$x_{21} = -7.59218224617533$$
$$x_{22} = 80.3724120543389$$
$$x_{23} = 71.9948316447661$$
$$x_{24} = 38.484510006475$$
$$x_{25} = -53.6688744988256$$
$$x_{26} = 32.2013246992954$$
$$x_{27} = 98.174770424681$$
$$x_{28} = 34.2957198016886$$
$$x_{29} = 30.1069295969022$$
$$x_{30} = -86.1319985859202$$
$$x_{31} = -79.8488132787406$$
$$x_{32} = -23.3001455141243$$
$$x_{33} = 41.6261026600648$$
$$x_{34} = 91.8915851175014$$
$$x_{35} = 16.4933614313464$$
$$x_{36} = -13.8753675533549$$
$$x_{37} = -44.2440965380563$$
$$x_{38} = -81.9432083811338$$
$$x_{39} = 100.269165527074$$
$$x_{40} = 8.11578102177363$$
$$x_{41} = -35.8665161284835$$
$$x_{42} = 74.0892267471593$$
$$x_{43} = 63.6172512351933$$
$$x_{44} = 54.1924732744239$$
$$x_{45} = 18.5877565337396$$
$$x_{46} = -57.857664703612$$
$$x_{47} = 67.8060414399797$$
$$x_{48} = 93.9859802198946$$
$$x_{49} = -84.037603483527$$
$$x_{50} = -59.9520598060052$$
$$x_{51} = 6.02138591938044$$
$$x_{52} = -93.4623814442964$$
$$x_{53} = -97.6511716490827$$
$$x_{54} = 47.9092879672443$$
$$x_{55} = -5.49778714378214$$
$$x_{56} = 58.3812634792103$$
$$x_{57} = -73.565627971561$$
$$x_{58} = 65.7116463375865$$
$$x_{59} = -42.1497014356631$$
$$x_{60} = 36.3901149040818$$
$$x_{61} = -75.6600230739542$$
$$x_{62} = -62.0464549083984$$
$$x_{63} = -22.2529479629277$$
$$x_{64} = -71.4712328691678$$
$$x_{65} = 52.0980781720307$$
$$x_{66} = 60.4756585816035$$
$$x_{67} = 56.2868683768171$$
$$x_{68} = -33.7721210260903$$
$$x_{69} = -0.261799387799149$$
$$x_{70} = -46.3384916404494$$
$$x_{71} = -9.68657734856853$$
$$x_{72} = -18.0641577581413$$
$$x_{73} = -27.4889357189107$$
$$x_{74} = 23.8237442897226$$
$$x_{75} = -711.308936650289$$
$$x_{76} = 96.0803753222878$$
$$x_{77} = 3.92699081698724$$
$$x_{78} = 45.8148928648512$$
$$x_{79} = -99.7455667514759$$
$$x_{80} = 82.4668071567321$$
$$x_{81} = -69.3768377667746$$
$$x_{82} = 10.2101761241668$$
$$x_{83} = -66.2352451131848$$
$$x_{84} = 14.3989663289532$$
$$x_{85} = 78.2780169519457$$
$$x_{86} = -31.6777259236971$$
$$x_{87} = -37.9609112308767$$
$$x_{88} = -77.7544181763474$$
$$x_{89} = 28.012534494509$$
$$x_{90} = -20.1585528605345$$
$$x_{91} = 89.7971900151083$$
$$x_{92} = -91.3679863419031$$