Graph of the function intersects the axis X at f = 0
so we need to solve the equation:
$$\sin{\left(\frac{x}{2} + \frac{\pi}{4} \right)} + \frac{1}{2} = 0$$
Solve this equationThe points of intersection with the axis X:
Analytical solution$$x_{1} = - \frac{5 \pi}{6}$$
$$x_{2} = \frac{11 \pi}{6}$$
Numerical solution$$x_{1} = -90.5825881785057$$
$$x_{2} = 30.8923277602996$$
$$x_{3} = -65.4498469497874$$
$$x_{4} = -15.1843644923507$$
$$x_{5} = 9.94837673636768$$
$$x_{6} = -40.317105721069$$
$$x_{7} = 35.081117965086$$
$$x_{8} = -2.61799387799149$$
$$x_{9} = 18.3259571459405$$
$$x_{10} = -44.5058959258554$$
$$x_{11} = -94.7713783832921$$
$$x_{12} = -82.2050077689329$$
$$x_{13} = -52.8834763354282$$
$$x_{14} = -6.80678408277789$$
$$x_{15} = -107.337748997651$$
$$x_{16} = -78.0162175641465$$
$$x_{17} = 22.5147473507269$$
$$x_{18} = 47.6474885794452$$
$$x_{19} = 613.134166225608$$
$$x_{20} = 72.7802298081635$$
$$x_{21} = 60.2138591938044$$
$$x_{22} = 43.4586983746588$$
$$x_{23} = 68.5914396033772$$
$$x_{24} = -19.3731546971371$$
$$x_{25} = -69.6386371545737$$
$$x_{26} = 93.7241808320955$$
$$x_{27} = -27.7507351067098$$
$$x_{28} = 97.9129710368819$$
$$x_{29} = 81.1578102177363$$
$$x_{30} = -253.945406165175$$
$$x_{31} = -195.302343298165$$
$$x_{32} = 56.025068989018$$
$$x_{33} = -57.0722665402146$$
$$x_{34} = -31.9395253114962$$
$$x_{35} = 5.75958653158129$$
$$x_{36} = 85.3466004225227$$