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$$- \sin{\left(x \right)} \operatorname{sign}{\left(\cos{\left(x \right)} - 1 \right)} = 0$$
Solve this equationThe roots of this equation
$$x_{1} = 37.6991118430775$$
$$x_{2} = 6.28318530717959$$
$$x_{3} = 87.9645943005142$$
$$x_{4} = 72.2566310325652$$
$$x_{5} = 9.42477796076938$$
$$x_{6} = -87.9645943005142$$
$$x_{7} = -59.6902604182061$$
$$x_{8} = 28.2743338823081$$
$$x_{9} = 43.9822971502571$$
$$x_{10} = 47.1238898038469$$
$$x_{11} = 84.8230016469244$$
$$x_{12} = 25.1327412287183$$
$$x_{13} = 91.106186954104$$
$$x_{14} = -18.8495559215388$$
$$x_{15} = 56.5486677646163$$
$$x_{16} = -91.106186954104$$
$$x_{17} = 18.8495559215388$$
$$x_{18} = -75.398223686155$$
$$x_{19} = -75.398223686155$$
$$x_{20} = -94.2477796076938$$
$$x_{21} = -40.8407044966673$$
$$x_{22} = 97.3893722612836$$
$$x_{23} = 3.14159265358979$$
$$x_{24} = -43.9822971502571$$
$$x_{25} = -84.8230016469244$$
$$x_{26} = -3.14159265358979$$
$$x_{27} = 0$$
$$x_{28} = -6.28318530717957$$
$$x_{29} = -50.2654824574367$$
$$x_{30} = -97.3893722612836$$
$$x_{31} = -25.1327412287183$$
$$x_{32} = 56.5486677646163$$
$$x_{33} = -62.8318530717959$$
$$x_{34} = -2642.07942166902$$
$$x_{35} = -78.5398163397448$$
$$x_{36} = 21.9911485751286$$
$$x_{37} = -72.2566310325652$$
$$x_{38} = 69.1150383789755$$
$$x_{39} = 50.2654824574367$$
$$x_{40} = 100.530964914873$$
$$x_{41} = 53.4070751110265$$
$$x_{42} = 12.5663706143592$$
$$x_{43} = -113.097335529233$$
$$x_{44} = 75.398223686155$$
$$x_{45} = -31.4159265358979$$
$$x_{46} = -37.6991118430775$$
$$x_{47} = -56.5486677646163$$
$$x_{48} = -21.9911485751286$$
$$x_{49} = -15.707963267949$$
$$x_{50} = 81.6814089933346$$
$$x_{51} = -232.477856365645$$
$$x_{52} = -69.1150383789755$$
$$x_{53} = 34.5575191894877$$
$$x_{54} = -87.9645943005142$$
$$x_{55} = 6.28318530717959$$
$$x_{56} = 18.8495559215388$$
$$x_{57} = -9.42477796076938$$
$$x_{58} = 78.5398163397448$$
$$x_{59} = -53.4070751110265$$
$$x_{60} = -34.5575191894877$$
$$x_{61} = -100.530964914873$$
$$x_{62} = 31.4159265358979$$
$$x_{63} = -267.035375555132$$
$$x_{64} = -25.1327412287183$$
$$x_{65} = -12.5663706143592$$
$$x_{66} = 40.8407044966673$$
$$x_{67} = -47.1238898038469$$
$$x_{68} = -81.6814089933346$$
$$x_{69} = -28.2743338823081$$
$$x_{70} = -65.9734457253857$$
$$x_{71} = 65.9734457253857$$
$$x_{72} = 15.707963267949$$
$$x_{73} = 94.2477796076938$$
$$x_{74} = 62.8318530717959$$
$$x_{75} = -31.4159265358979$$
$$x_{76} = 59.6902604182061$$
The values of the extrema at the points:
(37.6991118430775, 0)
(6.28318530717959, 0)
(87.9645943005142, 0)
(72.2566310325652, 2)
(9.42477796076938, 2)
(-87.9645943005142, 0)
(-59.6902604182061, 2)
(28.2743338823081, 2)
(43.9822971502571, 0)
(47.1238898038469, 2)
(84.8230016469244, 2)
(25.1327412287183, 0)
(91.106186954104, 2)
(-18.8495559215388, 0)
(56.5486677646163, 0)
(-91.106186954104, 2)
(18.8495559215388, 0)
(-75.398223686155, 0)
(-75.398223686155, 0)
(-94.2477796076938, 0)
(-40.8407044966673, 2)
(97.3893722612836, 2)
(3.14159265358979, 2)
(-43.9822971502571, 0)
(-84.8230016469244, 2)
(-3.14159265358979, 2)
(0, 0)
(-6.28318530717957, 0)
(-50.2654824574367, 0)
(-97.3893722612836, 2)
(-25.1327412287183, 0)
(56.5486677646163, 0)
(-62.8318530717959, 0)
(-2642.07942166902, 2)
(-78.5398163397448, 2)
(21.9911485751286, 2)
(-72.2566310325652, 2)
(69.1150383789755, 0)
(50.2654824574367, 0)
(100.530964914873, 0)
(53.4070751110265, 2)
(12.5663706143592, 0)
(-113.097335529233, 0)
(75.398223686155, 0)
(-31.4159265358979, 0)
(-37.6991118430775, 0)
(-56.5486677646163, 0)
(-21.9911485751286, 2)
(-15.707963267949, 2)
(81.6814089933346, 0)
(-232.477856365645, 0)
(-69.1150383789755, 0)
(34.5575191894877, 2)
(-87.9645943005142, 0)
(6.28318530717959, 0)
(18.8495559215388, 0)
(-9.42477796076938, 2)
(78.5398163397448, 2)
(-53.4070751110265, 2)
(-34.5575191894877, 2)
(-100.530964914873, 0)
(31.4159265358979, 0)
(-267.035375555132, 2)
(-25.1327412287183, 0)
(-12.5663706143592, 0)
(40.8407044966673, 2)
(-47.1238898038469, 2)
(-81.6814089933346, 0)
(-28.2743338823081, 2)
(-65.9734457253857, 2)
(65.9734457253857, 2)
(15.707963267949, 2)
(94.2477796076938, 0)
(62.8318530717959, 0)
(-31.4159265358979, 0)
(59.6902604182061, 2)
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:
$$x_{1} = 37.6991118430775$$
$$x_{2} = 6.28318530717959$$
$$x_{3} = 87.9645943005142$$
$$x_{4} = -87.9645943005142$$
$$x_{5} = 43.9822971502571$$
$$x_{6} = 25.1327412287183$$
$$x_{7} = -18.8495559215388$$
$$x_{8} = 56.5486677646163$$
$$x_{9} = 18.8495559215388$$
$$x_{10} = -75.398223686155$$
$$x_{11} = -75.398223686155$$
$$x_{12} = -94.2477796076938$$
$$x_{13} = -43.9822971502571$$
$$x_{14} = 0$$
$$x_{15} = -6.28318530717957$$
$$x_{16} = -50.2654824574367$$
$$x_{17} = -25.1327412287183$$
$$x_{18} = 56.5486677646163$$
$$x_{19} = -62.8318530717959$$
$$x_{20} = 69.1150383789755$$
$$x_{21} = 50.2654824574367$$
$$x_{22} = 100.530964914873$$
$$x_{23} = 12.5663706143592$$
$$x_{24} = -113.097335529233$$
$$x_{25} = 75.398223686155$$
$$x_{26} = -31.4159265358979$$
$$x_{27} = -37.6991118430775$$
$$x_{28} = -56.5486677646163$$
$$x_{29} = 81.6814089933346$$
$$x_{30} = -232.477856365645$$
$$x_{31} = -69.1150383789755$$
$$x_{32} = -87.9645943005142$$
$$x_{33} = 6.28318530717959$$
$$x_{34} = 18.8495559215388$$
$$x_{35} = -100.530964914873$$
$$x_{36} = 31.4159265358979$$
$$x_{37} = -25.1327412287183$$
$$x_{38} = -12.5663706143592$$
$$x_{39} = -81.6814089933346$$
$$x_{40} = 94.2477796076938$$
$$x_{41} = 62.8318530717959$$
$$x_{42} = -31.4159265358979$$
Maxima of the function at points:
$$x_{42} = 72.2566310325652$$
$$x_{42} = 9.42477796076938$$
$$x_{42} = -59.6902604182061$$
$$x_{42} = 28.2743338823081$$
$$x_{42} = 47.1238898038469$$
$$x_{42} = 84.8230016469244$$
$$x_{42} = 91.106186954104$$
$$x_{42} = -91.106186954104$$
$$x_{42} = -40.8407044966673$$
$$x_{42} = 97.3893722612836$$
$$x_{42} = 3.14159265358979$$
$$x_{42} = -84.8230016469244$$
$$x_{42} = -3.14159265358979$$
$$x_{42} = -97.3893722612836$$
$$x_{42} = -2642.07942166902$$
$$x_{42} = -78.5398163397448$$
$$x_{42} = 21.9911485751286$$
$$x_{42} = -72.2566310325652$$
$$x_{42} = 53.4070751110265$$
$$x_{42} = -21.9911485751286$$
$$x_{42} = -15.707963267949$$
$$x_{42} = 34.5575191894877$$
$$x_{42} = -9.42477796076938$$
$$x_{42} = 78.5398163397448$$
$$x_{42} = -53.4070751110265$$
$$x_{42} = -34.5575191894877$$
$$x_{42} = -267.035375555132$$
$$x_{42} = 40.8407044966673$$
$$x_{42} = -47.1238898038469$$
$$x_{42} = -28.2743338823081$$
$$x_{42} = -65.9734457253857$$
$$x_{42} = 65.9734457253857$$
$$x_{42} = 15.707963267949$$
$$x_{42} = 59.6902604182061$$
Decreasing at intervals
$$\left[100.530964914873, \infty\right)$$
Increasing at intervals
$$\left(-\infty, -232.477856365645\right]$$