El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$\cos{\left(4 x + \frac{\pi}{6} \right)} = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = \frac{\pi}{12}$$
$$x_{2} = \frac{\pi}{3}$$
Solución numérica$$x_{1} = -75.9218224617533$$
$$x_{2} = -24.0855436775217$$
$$x_{3} = 40.317105721069$$
$$x_{4} = 78.0162175641465$$
$$x_{5} = -46.0766922526503$$
$$x_{6} = -87.7027949127151$$
$$x_{7} = -71.9948316447661$$
$$x_{8} = -6.02138591938044$$
$$x_{9} = -65.7116463375865$$
$$x_{10} = 76.4454212373516$$
$$x_{11} = 67.8060414399797$$
$$x_{12} = 44.2440965380563$$
$$x_{13} = -97.9129710368819$$
$$x_{14} = -9.94837673636768$$
$$x_{15} = -43.720497762458$$
$$x_{16} = -7.59218224617533$$
$$x_{17} = 12.0427718387609$$
$$x_{18} = 4.18879020478639$$
$$x_{19} = 98.4365698124802$$
$$x_{20} = 88.2263936883134$$
$$x_{21} = 100.007366139275$$
$$x_{22} = -23.3001455141243$$
$$x_{23} = -53.9306738866248$$
$$x_{24} = 74.0892267471593$$
$$x_{25} = -28.012534494509$$
$$x_{26} = -13.8753675533549$$
$$x_{27} = 15.1843644923507$$
$$x_{28} = 23.8237442897226$$
$$x_{29} = 0.261799387799149$$
$$x_{30} = -93.9859802198946$$
$$x_{31} = -39.7935069454707$$
$$x_{32} = 45.8148928648512$$
$$x_{33} = -60.9992573572018$$
$$x_{34} = -64.1408500107916$$
$$x_{35} = -51.5744793964324$$
$$x_{36} = 19.8967534727354$$
$$x_{37} = 89.7971900151083$$
$$x_{38} = 1.83259571459405$$
$$x_{39} = 41.8879020478639$$
$$x_{40} = 56.025068989018$$
$$x_{41} = -50.0036830696375$$
$$x_{42} = 63.8790506229925$$
$$x_{43} = 80.3724120543389$$
$$x_{44} = 96.0803753222878$$
$$x_{45} = 34.0339204138894$$
$$x_{46} = -90.0589894029074$$
$$x_{47} = 84.2994028713261$$
$$x_{48} = 66.2352451131848$$
$$x_{49} = -73.565627971561$$
$$x_{50} = 22.2529479629277$$
$$x_{51} = -21.7293491873294$$
$$x_{52} = -61.7846555205993$$
$$x_{53} = -82.2050077689329$$
$$x_{54} = -25.6563400043166$$
$$x_{55} = -2.0943951023932$$
$$x_{56} = 63.093652459595$$
$$x_{57} = 37.9609112308767$$
$$x_{58} = -76.7072206251508$$
$$x_{59} = 59.9520598060052$$
$$x_{60} = 26.1799387799149$$
$$x_{61} = -79.8488132787406$$
$$x_{62} = 8.11578102177363$$
$$x_{63} = 4.97418836818384$$
$$x_{64} = -68.0678408277789$$
$$x_{65} = 85.870199198121$$
$$x_{66} = -3.66519142918809$$
$$x_{67} = 81.9432083811338$$
$$x_{68} = 33.248522250492$$
$$x_{69} = -20.1585528605345$$
$$x_{70} = -91.6297857297023$$
$$x_{71} = -47.6474885794452$$
$$x_{72} = -57.857664703612$$
$$x_{73} = 52.0980781720307$$
$$x_{74} = -42.1497014356631$$
$$x_{75} = -83.7758040957278$$
$$x_{76} = 30.1069295969022$$
$$x_{77} = -17.8023583703422$$
$$x_{78} = 70.162235930172$$
$$x_{79} = 36.3901149040818$$
$$x_{80} = 48.1710873550435$$
$$x_{81} = 18.3259571459405$$
$$x_{82} = 15.9697626557481$$
$$x_{83} = -95.5567765466895$$
$$x_{84} = -35.8665161284835$$
$$x_{85} = -40.5789051088682$$
$$x_{86} = 14.3989663289532$$
$$x_{87} = -29.5833308213039$$
$$x_{88} = 58.3812634792103$$
$$x_{89} = 83.5140047079287$$
$$x_{90} = 62.3082542961976$$
$$x_{91} = 92.1533845053006$$
$$x_{92} = -86.1319985859202$$
$$x_{93} = -69.6386371545737$$
$$x_{94} = -31.9395253114962$$