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$$\frac{2 \sin{\left(x \right)} \cos{\left(x \right)}}{x} - \frac{\sin^{2}{\left(x \right)}}{x^{2}} = 0$$
Solve this equationThe roots of this equation
$$x_{1} = -61.2528940466862$$
$$x_{2} = -86.3880101981266$$
$$x_{3} = 53.4070751110265$$
$$x_{4} = 72.2566310325652$$
$$x_{5} = -9.42477796076938$$
$$x_{6} = -59.6902604182061$$
$$x_{7} = 42.3997088362447$$
$$x_{8} = 20.3958423573092$$
$$x_{9} = 14.1017251335659$$
$$x_{10} = -95.8133575027966$$
$$x_{11} = -114.663771308444$$
$$x_{12} = 80.1043708909521$$
$$x_{13} = 12.5663706143592$$
$$x_{14} = -14.1017251335659$$
$$x_{15} = 95.8133575027966$$
$$x_{16} = -64.3948849627586$$
$$x_{17} = 37.6991118430775$$
$$x_{18} = -23.5407082923052$$
$$x_{19} = 64.3948849627586$$
$$x_{20} = -42.3997088362447$$
$$x_{21} = -20.3958423573092$$
$$x_{22} = 58.1108600600615$$
$$x_{23} = 7.78988375114457$$
$$x_{24} = 67.5368388204916$$
$$x_{25} = 15.707963267949$$
$$x_{26} = 92.6715879363332$$
$$x_{27} = -97.3893722612836$$
$$x_{28} = -21.9911485751286$$
$$x_{29} = 6.28318530717959$$
$$x_{30} = -83.2461991121237$$
$$x_{31} = -6.28318530717959$$
$$x_{32} = 34.5575191894877$$
$$x_{33} = -51.8266315338985$$
$$x_{34} = -2678.20755049327$$
$$x_{35} = -125.663706143592$$
$$x_{36} = -94.2477796076938$$
$$x_{37} = -67.5368388204916$$
$$x_{38} = 48.6844162648433$$
$$x_{39} = 28.2743338823081$$
$$x_{40} = -31.4159265358979$$
$$x_{41} = 59.6902604182061$$
$$x_{42} = -75.398223686155$$
$$x_{43} = -1.16556118520721$$
$$x_{44} = -81.6814089933346$$
$$x_{45} = -37.6991118430775$$
$$x_{46} = -1740.44233008875$$
$$x_{47} = 197.920337176157$$
$$x_{48} = -80.1043708909521$$
$$x_{49} = -17.2497818346079$$
$$x_{50} = -7.78988375114457$$
$$x_{51} = -50.2654824574367$$
$$x_{52} = 94.2477796076938$$
$$x_{53} = -29.8283692130955$$
$$x_{54} = 36.1144715353049$$
$$x_{55} = 56.5486677646163$$
$$x_{56} = -45.5421150692309$$
$$x_{57} = 87.9645943005142$$
$$x_{58} = 65.9734457253857$$
$$x_{59} = 70.6787605627689$$
$$x_{60} = 73.8206542907788$$
$$x_{61} = -53.4070751110265$$
$$x_{62} = 43.9822971502571$$
$$x_{63} = 86.3880101981266$$
$$x_{64} = -15.707963267949$$
$$x_{65} = -36.1144715353049$$
$$x_{66} = -62.8318530717959$$
$$x_{67} = -18.8495559215388$$
$$x_{68} = 23.5407082923052$$
$$x_{69} = -89.5298059530594$$
$$x_{70} = 45.5421150692309$$
$$x_{71} = -72.2566310325652$$
$$x_{72} = 4.60421677720058$$
$$x_{73} = 89.5298059530594$$
$$x_{74} = 78.5398163397448$$
$$x_{75} = -73.8206542907788$$
$$x_{76} = 29.8283692130955$$
$$x_{77} = -87.9645943005142$$
$$x_{78} = -43.9822971502571$$
$$x_{79} = 26.6848024909251$$
$$x_{80} = 21.9911485751286$$
$$x_{81} = -58.1108600600615$$
$$x_{82} = -10.9499436485412$$
$$x_{83} = 51.8266315338985$$
$$x_{84} = 81.6814089933346$$
$$x_{85} = -28.2743338823081$$
$$x_{86} = -65.9734457253857$$
$$x_{87} = 50.2654824574367$$
$$x_{88} = 100.530964914873$$
$$x_{89} = -39.2571723324086$$
The values of the extrema at the points:
(-61.2528940466862, -0.0163246714689743)
(-86.3880101981266, -0.0115752926793239)
(53.4070751110265, 4.05057601793315e-32)
(72.2566310325652, 5.6146090061508e-31)
(-9.42477796076938, -1.43216509716637e-32)
(-59.6902604182061, -2.51765268789636e-32)
(42.3997088362447, 0.0235817882463307)
(20.3958423573092, 0.0490001524829528)
(14.1017251335659, 0.0708242711210408)
(-95.8133575027966, -0.0104366739072752)
(-114.663771308444, -0.00872098461732392)
(80.1043708909521, 0.0124832269403218)
(12.5663706143592, 1.90955346288849e-32)
(-14.1017251335659, -0.0708242711210408)
(95.8133575027966, 0.0104366739072752)
(-64.3948849627586, -0.0155282475514317)
(37.6991118430775, 5.72866038866547e-32)
(-23.5407082923052, -0.0424604502887016)
(64.3948849627586, 0.0155282475514317)
(-42.3997088362447, -0.0235817882463307)
(-20.3958423573092, -0.0490001524829528)
(58.1108600600615, 0.0172072134440586)
(7.78988375114457, 0.127844922574794)
(67.5368388204916, 0.0148059223769658)
(15.707963267949, 2.38694182861061e-32)
(92.6715879363332, 0.0107904797231539)
(-97.3893722612836, -4.83455425149761e-31)
(-21.9911485751286, -3.34171856005486e-32)
(6.28318530717959, 9.54776731444245e-33)
(-83.2461991121237, -0.0120121271188891)
(-6.28318530717959, -9.54776731444245e-33)
(34.5575191894877, 1.40770552330931e-31)
(-51.8266315338985, -0.0192933035363155)
(-2678.20755049327, -0.000373384043728018)
(-125.663706143592, -1.90955346288849e-31)
(-94.2477796076938, -1.24937720620631e-31)
(-67.5368388204916, -0.0148059223769658)
(48.6844162648433, 0.0205382874085413)
(28.2743338823081, 4.2964952914991e-32)
(-31.4159265358979, -4.77388365722123e-32)
(59.6902604182061, 2.51765268789636e-32)
(-75.398223686155, -1.14573207773309e-31)
(-1.16556118520721, -0.724611353776708)
(-81.6814089933346, -1.88255223925938e-31)
(-37.6991118430775, -5.72866038866547e-32)
(-1740.44233008875, -2.11977620970517e-30)
(197.920337176157, 4.37573096585357e-32)
(-80.1043708909521, -0.0124832269403218)
(-17.2497818346079, -0.0579230818110724)
(-7.78988375114457, -0.127844922574794)
(-50.2654824574367, -7.63821385155396e-32)
(94.2477796076938, 1.24937720620631e-31)
(-29.8283692130955, -0.0335157141235985)
(36.1144715353049, 0.0276844243853039)
(56.5486677646163, 8.59299058299821e-32)
(-45.5421150692309, -0.021955051448177)
(87.9645943005142, 1.33668742402194e-31)
(65.9734457253857, 1.45857698861786e-32)
(70.6787605627689, 0.0141478139878745)
(73.8206542907788, 0.0135457228854227)
(-53.4070751110265, -4.05057601793315e-32)
(43.9822971502571, 6.68343712010972e-32)
(86.3880101981266, 0.0115752926793239)
(-15.707963267949, -2.38694182861061e-32)
(-36.1144715353049, -0.0276844243853039)
(-62.8318530717959, -9.54776731444245e-32)
(-18.8495559215388, -2.86433019433273e-32)
(23.5407082923052, 0.0424604502887016)
(-89.5298059530594, -0.0111691162634939)
(45.5421150692309, 0.021955051448177)
(-72.2566310325652, -5.6146090061508e-31)
(4.60421677720058, 0.214660688386019)
(89.5298059530594, 0.0111691162634939)
(78.5398163397448, 3.07074756807772e-33)
(-73.8206542907788, -0.0135457228854227)
(29.8283692130955, 0.0335157141235985)
(-87.9645943005142, -1.33668742402194e-31)
(-43.9822971502571, -6.68343712010972e-32)
(26.6848024909251, 0.0374613617155508)
(21.9911485751286, 3.34171856005486e-32)
(-58.1108600600615, -0.0172072134440586)
(-10.9499436485412, -0.0911346506917966)
(51.8266315338985, 0.0192933035363155)
(81.6814089933346, 1.88255223925938e-31)
(-28.2743338823081, -4.2964952914991e-32)
(-65.9734457253857, -1.45857698861786e-32)
(50.2654824574367, 7.63821385155396e-32)
(100.530964914873, 1.52764277031079e-31)
(-39.2571723324086, -0.0254689206534694)
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:
$$x_{1} = -61.2528940466862$$
$$x_{2} = -86.3880101981266$$
$$x_{3} = 53.4070751110265$$
$$x_{4} = 72.2566310325652$$
$$x_{5} = -95.8133575027966$$
$$x_{6} = -114.663771308444$$
$$x_{7} = 12.5663706143592$$
$$x_{8} = -14.1017251335659$$
$$x_{9} = -64.3948849627586$$
$$x_{10} = 37.6991118430775$$
$$x_{11} = -23.5407082923052$$
$$x_{12} = -42.3997088362447$$
$$x_{13} = -20.3958423573092$$
$$x_{14} = 15.707963267949$$
$$x_{15} = 6.28318530717959$$
$$x_{16} = -83.2461991121237$$
$$x_{17} = 34.5575191894877$$
$$x_{18} = -51.8266315338985$$
$$x_{19} = -2678.20755049327$$
$$x_{20} = -67.5368388204916$$
$$x_{21} = 28.2743338823081$$
$$x_{22} = 59.6902604182061$$
$$x_{23} = -1.16556118520721$$
$$x_{24} = 197.920337176157$$
$$x_{25} = -80.1043708909521$$
$$x_{26} = -17.2497818346079$$
$$x_{27} = -7.78988375114457$$
$$x_{28} = 94.2477796076938$$
$$x_{29} = -29.8283692130955$$
$$x_{30} = 56.5486677646163$$
$$x_{31} = -45.5421150692309$$
$$x_{32} = 87.9645943005142$$
$$x_{33} = 65.9734457253857$$
$$x_{34} = 43.9822971502571$$
$$x_{35} = -36.1144715353049$$
$$x_{36} = -89.5298059530594$$
$$x_{37} = 78.5398163397448$$
$$x_{38} = -73.8206542907788$$
$$x_{39} = 21.9911485751286$$
$$x_{40} = -58.1108600600615$$
$$x_{41} = -10.9499436485412$$
$$x_{42} = 81.6814089933346$$
$$x_{43} = 50.2654824574367$$
$$x_{44} = 100.530964914873$$
$$x_{45} = -39.2571723324086$$
Maxima of the function at points:
$$x_{45} = -9.42477796076938$$
$$x_{45} = -59.6902604182061$$
$$x_{45} = 42.3997088362447$$
$$x_{45} = 20.3958423573092$$
$$x_{45} = 14.1017251335659$$
$$x_{45} = 80.1043708909521$$
$$x_{45} = 95.8133575027966$$
$$x_{45} = 64.3948849627586$$
$$x_{45} = 58.1108600600615$$
$$x_{45} = 7.78988375114457$$
$$x_{45} = 67.5368388204916$$
$$x_{45} = 92.6715879363332$$
$$x_{45} = -97.3893722612836$$
$$x_{45} = -21.9911485751286$$
$$x_{45} = -6.28318530717959$$
$$x_{45} = -125.663706143592$$
$$x_{45} = -94.2477796076938$$
$$x_{45} = 48.6844162648433$$
$$x_{45} = -31.4159265358979$$
$$x_{45} = -75.398223686155$$
$$x_{45} = -81.6814089933346$$
$$x_{45} = -37.6991118430775$$
$$x_{45} = -1740.44233008875$$
$$x_{45} = -50.2654824574367$$
$$x_{45} = 36.1144715353049$$
$$x_{45} = 70.6787605627689$$
$$x_{45} = 73.8206542907788$$
$$x_{45} = -53.4070751110265$$
$$x_{45} = 86.3880101981266$$
$$x_{45} = -15.707963267949$$
$$x_{45} = -62.8318530717959$$
$$x_{45} = -18.8495559215388$$
$$x_{45} = 23.5407082923052$$
$$x_{45} = 45.5421150692309$$
$$x_{45} = -72.2566310325652$$
$$x_{45} = 4.60421677720058$$
$$x_{45} = 89.5298059530594$$
$$x_{45} = 29.8283692130955$$
$$x_{45} = -87.9645943005142$$
$$x_{45} = -43.9822971502571$$
$$x_{45} = 26.6848024909251$$
$$x_{45} = 51.8266315338985$$
$$x_{45} = -28.2743338823081$$
$$x_{45} = -65.9734457253857$$
Decreasing at intervals
$$\left[197.920337176157, \infty\right)$$
Increasing at intervals
$$\left(-\infty, -2678.20755049327\right]$$