El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$\left(2 \sin{\left(x \right)} \cos{\left(x \right)} + \sin{\left(2 x \right)}\right) + 3 \cos{\left(2 x \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución numérica$$x_{1} = 56.0572709029926$$
$$x_{2} = 40.3493076350437$$
$$x_{3} = -90.0267874889328$$
$$x_{4} = -74.3188242209838$$
$$x_{5} = -3.63298951521346$$
$$x_{6} = -39.7613050314961$$
$$x_{7} = 46.6324929422232$$
$$x_{8} = -17.7701564563675$$
$$x_{9} = -9.91617482239304$$
$$x_{10} = -0.491396861623665$$
$$x_{11} = 49.774085595813$$
$$x_{12} = 12.0749737527355$$
$$x_{13} = -38.1905087047012$$
$$x_{14} = 21.4997517135049$$
$$x_{15} = -33.4781197243165$$
$$x_{16} = 41.9201039618385$$
$$x_{17} = -63.3232499334195$$
$$x_{18} = 48.2032892690181$$
$$x_{19} = 54.4864745761977$$
$$x_{20} = -19.3409527831624$$
$$x_{21} = 1.07939946517123$$
$$x_{22} = 34.0661223278641$$
$$x_{23} = -77.4604168745736$$
$$x_{24} = 19.92895538671$$
$$x_{25} = -41.332101358291$$
$$x_{26} = -24.0533417635471$$
$$x_{27} = 60.7696598833773$$
$$x_{28} = 65.482048863762$$
$$x_{29} = -85.3143985085481$$
$$x_{30} = -75.8896205477787$$
$$x_{31} = 35.636918654659$$
$$x_{32} = 26.2121406938896$$
$$x_{33} = -47.6152866654706$$
$$x_{34} = -97.8807691229073$$
$$x_{35} = -82.1728058549583$$
$$x_{36} = -31.9073233975216$$
$$x_{37} = 62.3404562101722$$
$$x_{38} = -96.3099727961124$$
$$x_{39} = 85.9024011120956$$
$$x_{40} = 79.6192158049161$$
$$x_{41} = 78.0484194781212$$
$$x_{42} = 24.6413443670947$$
$$x_{43} = 92.1855864192752$$
$$x_{44} = -8.34537849559815$$
$$x_{45} = 43.4909002886334$$
$$x_{46} = -46.0444903386757$$
$$x_{47} = 90.6147900924803$$
$$x_{48} = -52.3276756458553$$
$$x_{49} = 100.03956805325$$
$$x_{50} = 2.65019579196613$$
$$x_{51} = -53.8984719726501$$
$$x_{52} = -55.469268299445$$
$$x_{53} = -91.5975838157277$$
$$x_{54} = 57.6280672297875$$
$$x_{55} = -61.7524536066246$$
$$x_{56} = 5.79178844555592$$
$$x_{57} = 32.4953260010692$$
$$x_{58} = 4.22099211876103$$
$$x_{59} = -60.1816572798297$$
$$x_{60} = 84.3316047853008$$
$$x_{61} = 68.6236415173518$$
$$x_{62} = -44.4736940118808$$
$$x_{63} = -66.4648425870093$$
$$x_{64} = -22.4825454367522$$
$$x_{65} = -30.3365270707267$$
$$x_{66} = -83.7436021817532$$
$$x_{67} = -99.4515654497022$$
$$x_{68} = 23.0705480402998$$
$$x_{69} = 93.7563827460701$$
$$x_{70} = 71.7652341709416$$
$$x_{71} = 13.6457700795304$$
$$x_{72} = 186.433366026969$$
$$x_{73} = -25.624138090342$$
$$x_{74} = -11.4869711491879$$
$$x_{75} = 27.7829370206845$$
$$x_{76} = 98.4687717264548$$
$$x_{77} = -80.6020095281634$$
$$x_{78} = 82.7608084585058$$
$$x_{79} = -68.0356389138042$$
$$x_{80} = 70.1944378441467$$
$$x_{81} = 18.3581590599151$$
$$x_{82} = 10.5041774259406$$
$$x_{83} = -88.4559911621379$$
$$x_{84} = 63.9112525369671$$
$$x_{85} = -118.301121371241$$
$$x_{86} = -69.6064352405991$$
$$x_{87} = 76.4776231513263$$
$$x_{88} = -16.1993601295726$$
$$x_{89} = -2.06219318841856$$