Graph of the function intersects the axis X at f = 0
so we need to solve the equation:
$$2 \sin{\left(2 x \right)} + 1 = 0$$
Solve this equationThe points of intersection with the axis X:
Analytical solution$$x_{1} = - \frac{\pi}{12}$$
$$x_{2} = \frac{7 \pi}{12}$$
Numerical solution$$x_{1} = 20.6821516361328$$
$$x_{2} = 62.5700536839967$$
$$x_{3} = 12.30457122656$$
$$x_{4} = 81.4196096055355$$
$$x_{5} = -81.9432083811338$$
$$x_{6} = -31.6777259236971$$
$$x_{7} = 58.3812634792103$$
$$x_{8} = -53.6688744988256$$
$$x_{9} = 8.11578102177363$$
$$x_{10} = -1926.05809603834$$
$$x_{11} = -75.6600230739542$$
$$x_{12} = 78.2780169519457$$
$$x_{13} = 21.7293491873294$$
$$x_{14} = -95.5567765466895$$
$$x_{15} = -66.2352451131848$$
$$x_{16} = -6.54498469497874$$
$$x_{17} = 40.5789051088682$$
$$x_{18} = 90.8443875663049$$
$$x_{19} = -22.2529479629277$$
$$x_{20} = 1.83259571459405$$
$$x_{21} = 6.02138591938044$$
$$x_{22} = 93.9859802198946$$
$$x_{23} = -15.9697626557481$$
$$x_{24} = 84.5612022591253$$
$$x_{25} = -42.1497014356631$$
$$x_{26} = -94.5095789954929$$
$$x_{27} = -29.5833308213039$$
$$x_{28} = -97.6511716490827$$
$$x_{29} = 52.0980781720307$$
$$x_{30} = -79.8488132787406$$
$$x_{31} = 42.6733002112614$$
$$x_{32} = 65.7116463375865$$
$$x_{33} = 100.269165527074$$
$$x_{34} = -57.857664703612$$
$$x_{35} = -73.565627971561$$
$$x_{36} = -45.2912940892529$$
$$x_{37} = -89.27359123951$$
$$x_{38} = -50.5272818452358$$
$$x_{39} = -88.2263936883134$$
$$x_{40} = 23.8237442897226$$
$$x_{41} = 34.2957198016886$$
$$x_{42} = -59.9520598060052$$
$$x_{43} = -28.5361332701073$$
$$x_{44} = 71.9948316447661$$
$$x_{45} = -91.3679863419031$$
$$x_{46} = -37.9609112308767$$
$$x_{47} = 80.3724120543389$$
$$x_{48} = -67.2824426643814$$
$$x_{49} = 127.496301858186$$
$$x_{50} = -86.1319985859202$$
$$x_{51} = 14.3989663289532$$
$$x_{52} = 89.7971900151083$$
$$x_{53} = -44.2440965380563$$
$$x_{54} = -0.261799387799149$$
$$x_{55} = -20.1585528605345$$
$$x_{56} = 64.6644487863899$$
$$x_{57} = 87.7027949127151$$
$$x_{58} = 96.0803753222878$$
$$x_{59} = 45.8148928648512$$
$$x_{60} = -35.8665161284835$$
$$x_{61} = 43.720497762458$$
$$x_{62} = 56.2868683768171$$
$$x_{63} = 67.8060414399797$$
$$x_{64} = -1.30899693899575$$
$$x_{65} = 74.0892267471593$$
$$x_{66} = 59.4284610304069$$
$$x_{67} = -9.68657734856853$$
$$x_{68} = -51.5744793964324$$
$$x_{69} = -17.0169602069447$$
$$x_{70} = -72.5184304203644$$
$$x_{71} = 50.0036830696375$$
$$x_{72} = 36.3901149040818$$
$$x_{73} = 18.5877565337396$$
$$x_{74} = 37.4373124552784$$
$$x_{75} = 28.012534494509$$
$$x_{76} = -7.59218224617533$$
$$x_{77} = 86.6555973615185$$
$$x_{78} = 30.1069295969022$$
$$x_{79} = -64.1408500107916$$
$$x_{80} = -13.8753675533549$$
$$x_{81} = -23.3001455141243$$
$$x_{82} = 15.4461638801498$$