In order to find the extrema, we need to solve the equation
$$\frac{d}{d x} f{\left(x \right)} = 0$$
(the derivative equals zero),
and the roots of this equation are the extrema of this function:
$$\frac{d}{d x} f{\left(x \right)} = $$
the first derivative$$- \frac{x \cos{\left(x \right)}}{\sin^{2}{\left(x \right)}} + \frac{1}{\sin{\left(x \right)}} = 0$$
Solve this equationThe roots of this equation
$$x_{1} = 4.93829501990806 \cdot 10^{-17}$$
$$x_{2} = -76.9560263103312$$
$$x_{3} = 20.3713029592876$$
$$x_{4} = 39.2444323611642$$
$$x_{5} = 89.5242209304172$$
$$x_{6} = 83.2401924707234$$
$$x_{7} = -7.72525183693771$$
$$x_{8} = 92.6661922776228$$
$$x_{9} = 36.1006222443756$$
$$x_{10} = 95.8081387868617$$
$$x_{11} = -17.2207552719308$$
$$x_{12} = 61.2447302603744$$
$$x_{13} = 70.6716857116195$$
$$x_{14} = 10.9041216594289$$
$$x_{15} = 2.01537897347346 \cdot 10^{-17}$$
$$x_{16} = 98.9500628243319$$
$$x_{17} = 80.0981286289451$$
$$x_{18} = 51.8169824872797$$
$$x_{19} = -10.9041216594289$$
$$x_{20} = -61.2447302603744$$
$$x_{21} = -89.5242209304172$$
$$x_{22} = 23.519452498689$$
$$x_{23} = -36.1006222443756$$
$$x_{24} = -58.1022547544956$$
$$x_{25} = 32.9563890398225$$
$$x_{26} = 29.811598790893$$
$$x_{27} = -83.2401924707234$$
$$x_{28} = -80.0981286289451$$
$$x_{29} = -45.5311340139913$$
$$x_{30} = 67.5294347771441$$
$$x_{31} = -29.811598790893$$
$$x_{32} = 17.2207552719308$$
$$x_{33} = 58.1022547544956$$
$$x_{34} = 76.9560263103312$$
$$x_{35} = -54.9596782878889$$
$$x_{36} = -67.5294347771441$$
$$x_{37} = 45.5311340139913$$
$$x_{38} = 54.9596782878889$$
$$x_{39} = 7.72525183693771$$
$$x_{40} = 64.3871195905574$$
$$x_{41} = -20.3713029592876$$
$$x_{42} = -32.9563890398225$$
$$x_{43} = -4.49340945790906$$
$$x_{44} = -95.8081387868617$$
$$x_{45} = -86.3822220347287$$
$$x_{46} = -42.3879135681319$$
$$x_{47} = -98.9500628243319$$
$$x_{48} = -14.0661939128315$$
$$x_{49} = -51.8169824872797$$
$$x_{50} = 4.49340945790906$$
$$x_{51} = 86.3822220347287$$
$$x_{52} = -39.2444323611642$$
$$x_{53} = -26.6660542588127$$
$$x_{54} = 48.6741442319544$$
$$x_{55} = -23.519452498689$$
$$x_{56} = -48.6741442319544$$
$$x_{57} = -64.3871195905574$$
$$x_{58} = 14.0661939128315$$
$$x_{59} = 26.6660542588127$$
$$x_{60} = 73.8138806006806$$
$$x_{61} = -70.6716857116195$$
$$x_{62} = 42.3879135681319$$
$$x_{63} = -92.6661922776228$$
$$x_{64} = -73.8138806006806$$
The values of the extrema at the points:
(4.93829501990806e-17, 1)
(-76.9560263103312, 76.9625232530508)
(20.3713029592876, 20.3958325218432)
(39.2444323611642, 39.2571709544892)
(89.5242209304172, 89.5298058369287)
(83.2401924707234, 83.2461989676591)
(-7.72525183693771, 7.78970576749272)
(92.6661922776228, -92.6715878316184)
(36.1006222443756, -36.1144697653324)
(95.8081387868617, 95.8133574080491)
(-17.2207552719308, -17.2497655675586)
(61.2447302603744, -61.2528936840213)
(70.6716857116195, 70.67876032672)
(10.9041216594289, -10.9498798698263)
(2.01537897347346e-17, 1)
(98.9500628243319, -98.9551157492084)
(80.0981286289451, -80.1043707288125)
(51.8169824872797, 51.8266309351384)
(-10.9041216594289, -10.9498798698263)
(-61.2447302603744, -61.2528936840213)
(-89.5242209304172, 89.5298058369287)
(23.519452498689, -23.5407018977364)
(-36.1006222443756, -36.1144697653324)
(-58.1022547544956, 58.1108596353238)
(32.9563890398225, 32.9715571143392)
(29.811598790893, -29.8283660710601)
(-83.2401924707234, 83.2461989676591)
(-80.0981286289451, -80.1043707288125)
(-45.5311340139913, 45.5421141867616)
(67.5294347771441, -67.5368385499393)
(-29.811598790893, -29.8283660710601)
(17.2207552719308, -17.2497655675586)
(58.1022547544956, 58.1108596353238)
(76.9560263103312, 76.9625232530508)
(-54.9596782878889, -54.9687751137703)
(-67.5294347771441, -67.5368385499393)
(45.5311340139913, 45.5421141867616)
(54.9596782878889, -54.9687751137703)
(7.72525183693771, 7.78970576749272)
(64.3871195905574, 64.3948846506362)
(-20.3713029592876, 20.3958325218432)
(-32.9563890398225, 32.9715571143392)
(-4.49340945790906, -4.6033388487517)
(-95.8081387868617, 95.8133574080491)
(-86.3822220347287, -86.3880100688583)
(-42.3879135681319, -42.399707742618)
(-98.9500628243319, -98.9551157492084)
(-14.0661939128315, 14.1016953304692)
(-51.8169824872797, 51.8266309351384)
(4.49340945790906, -4.6033388487517)
(86.3822220347287, -86.3880100688583)
(-39.2444323611642, 39.2571709544892)
(-26.6660542588127, 26.6847981018021)
(48.6741442319544, -48.6844155424824)
(-23.519452498689, -23.5407018977364)
(-48.6741442319544, -48.6844155424824)
(-64.3871195905574, 64.3948846506362)
(14.0661939128315, 14.1016953304692)
(26.6660542588127, 26.6847981018021)
(73.8138806006806, -73.8206540836068)
(-70.6716857116195, 70.67876032672)
(42.3879135681319, -42.399707742618)
(-92.6661922776228, -92.6715878316184)
(-73.8138806006806, -73.8206540836068)
Intervals of increase and decrease of the function:Let's find intervals where the function increases and decreases, as well as minima and maxima of the function, for this let's look how the function behaves itself in the extremas and at the slightest deviation from:
Minima of the function at points:
$$x_{1} = 4.93829501990806 \cdot 10^{-17}$$
$$x_{2} = -76.9560263103312$$
$$x_{3} = 20.3713029592876$$
$$x_{4} = 39.2444323611642$$
$$x_{5} = 89.5242209304172$$
$$x_{6} = 83.2401924707234$$
$$x_{7} = -7.72525183693771$$
$$x_{8} = 95.8081387868617$$
$$x_{9} = 70.6716857116195$$
$$x_{10} = 2.01537897347346 \cdot 10^{-17}$$
$$x_{11} = 51.8169824872797$$
$$x_{12} = -89.5242209304172$$
$$x_{13} = -58.1022547544956$$
$$x_{14} = 32.9563890398225$$
$$x_{15} = -83.2401924707234$$
$$x_{16} = -45.5311340139913$$
$$x_{17} = 58.1022547544956$$
$$x_{18} = 76.9560263103312$$
$$x_{19} = 45.5311340139913$$
$$x_{20} = 7.72525183693771$$
$$x_{21} = 64.3871195905574$$
$$x_{22} = -20.3713029592876$$
$$x_{23} = -32.9563890398225$$
$$x_{24} = -95.8081387868617$$
$$x_{25} = -14.0661939128315$$
$$x_{26} = -51.8169824872797$$
$$x_{27} = -39.2444323611642$$
$$x_{28} = -26.6660542588127$$
$$x_{29} = -64.3871195905574$$
$$x_{30} = 14.0661939128315$$
$$x_{31} = 26.6660542588127$$
$$x_{32} = -70.6716857116195$$
Maxima of the function at points:
$$x_{32} = 92.6661922776228$$
$$x_{32} = 36.1006222443756$$
$$x_{32} = -17.2207552719308$$
$$x_{32} = 61.2447302603744$$
$$x_{32} = 10.9041216594289$$
$$x_{32} = 98.9500628243319$$
$$x_{32} = 80.0981286289451$$
$$x_{32} = -10.9041216594289$$
$$x_{32} = -61.2447302603744$$
$$x_{32} = 23.519452498689$$
$$x_{32} = -36.1006222443756$$
$$x_{32} = 29.811598790893$$
$$x_{32} = -80.0981286289451$$
$$x_{32} = 67.5294347771441$$
$$x_{32} = -29.811598790893$$
$$x_{32} = 17.2207552719308$$
$$x_{32} = -54.9596782878889$$
$$x_{32} = -67.5294347771441$$
$$x_{32} = 54.9596782878889$$
$$x_{32} = -4.49340945790906$$
$$x_{32} = -86.3822220347287$$
$$x_{32} = -42.3879135681319$$
$$x_{32} = -98.9500628243319$$
$$x_{32} = 4.49340945790906$$
$$x_{32} = 86.3822220347287$$
$$x_{32} = 48.6741442319544$$
$$x_{32} = -23.519452498689$$
$$x_{32} = -48.6741442319544$$
$$x_{32} = 73.8138806006806$$
$$x_{32} = 42.3879135681319$$
$$x_{32} = -92.6661922776228$$
$$x_{32} = -73.8138806006806$$
Decreasing at intervals
$$\left[95.8081387868617, \infty\right)$$
Increasing at intervals
$$\left(-\infty, -95.8081387868617\right]$$