El gráfico de la función cruce el eje X con f = 0
o sea hay que resolver la ecuación:
$$4 \sin{\left(x + \frac{\pi}{4} \right)} - 3 = 0$$
Resolvermos esta ecuaciónPuntos de cruce con el eje X:
Solución analítica$$x_{1} = - \frac{\pi}{4} + \operatorname{asin}{\left(\frac{3}{4} \right)}$$
$$x_{2} = - \operatorname{asin}{\left(\frac{3}{4} \right)} + \frac{3 \pi}{4}$$
Solución numérica$$x_{1} = 75.4608876017391$$
$$x_{2} = 108.322282633264$$
$$x_{3} = 44.0449610658411$$
$$x_{4} = -23.6246088175075$$
$$x_{5} = -6.22052139159555$$
$$x_{6} = 6.34584922276362$$
$$x_{7} = -17.3414235103279$$
$$x_{8} = 45.490429561468$$
$$x_{9} = -43.9196332346731$$
$$x_{10} = -61.323720660585$$
$$x_{11} = -4.77505289596872$$
$$x_{12} = 89.4727267117251$$
$$x_{13} = -87.9019303849302$$
$$x_{14} = -42.4741647390462$$
$$x_{15} = -94.1851156921098$$
$$x_{16} = 51.7736148686476$$
$$x_{17} = -100.468300999289$$
$$x_{18} = 37.7617757586615$$
$$x_{19} = 0.0626639155840327$$
$$x_{20} = -67.6069059677646$$
$$x_{21} = 58.0568001758271$$
$$x_{22} = -56.4860038490322$$
$$x_{23} = 100.593628830457$$
$$x_{24} = -69.0523744633914$$
$$x_{25} = -92.7396471964829$$
$$x_{26} = -75.335559770571$$
$$x_{27} = 76.9063560973659$$
$$x_{28} = -207.282451221342$$
$$x_{29} = 70.6231707901863$$
$$x_{30} = -25.0700773131343$$
$$x_{31} = 62.8945169873799$$
$$x_{32} = -18.7868920059547$$
$$x_{33} = 26.6408736399292$$
$$x_{34} = 39.2072442542884$$
$$x_{35} = -31.3532626203139$$
$$x_{36} = -11.0582382031483$$
$$x_{37} = -8218.34371787532$$
$$x_{38} = -99.0228325036625$$
$$x_{39} = 81.7440729089187$$
$$x_{40} = 170049.63528592$$
$$x_{41} = -29.9077941246871$$
$$x_{42} = 18.9122198371228$$
$$x_{43} = 32.9240589471088$$
$$x_{44} = 1.50813241121086$$
$$x_{45} = 20.3576883327496$$
$$x_{46} = -12.5037066987751$$
$$x_{47} = 31.478590451482$$
$$x_{48} = 25.1954051443024$$
$$x_{49} = 88.0272582160982$$
$$x_{50} = 12.6290345299432$$
$$x_{51} = -37.6364479274935$$
$$x_{52} = -50.2028185418527$$
$$x_{53} = 64.3399854830067$$
$$x_{54} = 7.79131771839045$$
$$x_{55} = -86.4564618893033$$
$$x_{56} = -80.1732765821238$$
$$x_{57} = -81.6187450777506$$
$$x_{58} = -182.149709992624$$
$$x_{59} = 69.1777022945595$$
$$x_{60} = -36.1909794318667$$
$$x_{61} = -48.7573500462258$$
$$x_{62} = 94.3104435232778$$
$$x_{63} = 50.3281463730207$$
$$x_{64} = -62.7691891562118$$
$$x_{65} = 56.6113316802003$$
$$x_{66} = -55.0405353534054$$
$$x_{67} = 83.1895414045455$$
$$x_{68} = 95.7559120189047$$
$$x_{69} = -73.8900912749442$$
$$x_{70} = 14.07450302557$$