El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$6 \sin{\left(3 x \right)} + 2 \cos{\left(3 x \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = - \frac{\operatorname{atan}{\left(\frac{1}{3} \right)}}{3}$$
Solución numérica$$x_{1} = -39.9007571302696$$
$$x_{2} = -2.20164528719208$$
$$x_{3} = 23.9782934927229$$
$$x_{4} = -28.381584067107$$
$$x_{5} = -33.61757182309$$
$$x_{6} = 67.96059064298$$
$$x_{7} = 58.5358126822106$$
$$x_{8} = 32.3558739022956$$
$$x_{9} = 19.7895032879365$$
$$x_{10} = 92.0461343205017$$
$$x_{11} = 74.2437759501596$$
$$x_{12} = 1.98714491759431$$
$$x_{13} = -22.0983987599274$$
$$x_{14} = -9.53202814556826$$
$$x_{15} = -48.2783375398424$$
$$x_{16} = 89.9517392181085$$
$$x_{17} = 6.17593512238071$$
$$x_{18} = 41.780651863065$$
$$x_{19} = -17.909608555141$$
$$x_{20} = -20.0040036575342$$
$$x_{21} = -83.8830542805267$$
$$x_{22} = 94.1405294228949$$
$$x_{23} = 72.1493808477664$$
$$x_{24} = -41.9951522326628$$
$$x_{25} = 96.2349245252881$$
$$x_{26} = -46.1839424374492$$
$$x_{27} = -55.6087203982186$$
$$x_{28} = -92.2606346900995$$
$$x_{29} = -99.5910175484757$$
$$x_{30} = -53.5143252958254$$
$$x_{31} = -15.8152134527478$$
$$x_{32} = 98.3293196276813$$
$$x_{33} = -11.6264232479615$$
$$x_{34} = 100.423714730075$$
$$x_{35} = 54.3470224774242$$
$$x_{36} = 17.6951081855433$$
$$x_{37} = -120.534968572408$$
$$x_{38} = -73.4110787685607$$
$$x_{39} = 43.8750469654582$$
$$x_{40} = 78.4325661549459$$
$$x_{41} = 50.1582322726378$$
$$x_{42} = -59.797510603005$$
$$x_{43} = 87.8573441157153$$
$$x_{44} = -57.7031155006118$$
$$x_{45} = -50.3727326422356$$
$$x_{46} = -81.7886591781335$$
$$x_{47} = 52.252627375031$$
$$x_{48} = 26.0726885951161$$
$$x_{49} = -67.1278934613811$$
$$x_{50} = 80.5269612573392$$
$$x_{51} = 82.6213563597323$$
$$x_{52} = -26.2871889647138$$
$$x_{53} = -31.5231767206968$$
$$x_{54} = -44.089547335056$$
$$x_{55} = 4.08154001998751$$
$$x_{56} = 65.8661955405868$$
$$x_{57} = 30.2614787999025$$
$$x_{58} = 85.7629490133221$$
$$x_{59} = -70.2694861149709$$
$$x_{60} = 34.4502690046888$$
$$x_{61} = -90.1662395877063$$
$$x_{62} = -66.0806959101845$$
$$x_{63} = -97.4966224460825$$
$$x_{64} = -68.1750910125777$$
$$x_{65} = -77.5998689733471$$
$$x_{66} = -98.5438199972791$$
$$x_{67} = 63.7718004381936$$
$$x_{68} = 36.544664107082$$
$$x_{69} = -63.9863008077913$$
$$x_{70} = 56.4414175798174$$
$$x_{71} = 28.1670836975093$$
$$x_{72} = -24.1927938623206$$
$$x_{73} = 12.4591204295603$$
$$x_{74} = 48.0638371702446$$
$$x_{75} = -37.8063620278764$$
$$x_{76} = -61.8919057053981$$
$$x_{77} = 1522.51798925505$$
$$x_{78} = 10.3647253271671$$
$$x_{79} = 14.5535155319535$$
$$x_{80} = -0.107250184798881$$
$$x_{81} = -79.6942640757403$$
$$x_{82} = 21.8838983903297$$
$$x_{83} = 8.2703302247739$$
$$x_{84} = -13.7208183503547$$
$$x_{85} = 45.9694420678514$$
$$x_{86} = 70.0549857453732$$
$$x_{87} = -4.29604038958527$$
$$x_{88} = -75.5054738709539$$
$$x_{89} = -35.7119669254832$$
$$x_{90} = -85.9774493829199$$
$$x_{91} = -88.0718444853131$$
$$x_{92} = 76.3381710525528$$
$$x_{93} = 60.6302077846038$$