Para hallar los extremos hay que resolver la ecuación
$$\frac{d}{d x} f{\left(x \right)} = 0$$
(la derivada es igual a cero),
y las raíces de esta ecuación serán los extremos de esta función:
$$\frac{d}{d x} f{\left(x \right)} = $$
primera derivada$$- x e^{- x \cos{\left(x \right)} + \sin{\left(x \right)}} \sin{\left(x \right)} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = -15.707963267949$$
$$x_{2} = 0$$
$$x_{3} = -91.1998699041465$$
$$x_{4} = 81.6814089933346$$
$$x_{5} = -72.2566310325652$$
$$x_{6} = -34.9294771386704$$
$$x_{7} = 50.2654824574367$$
$$x_{8} = 69.5606259232977$$
$$x_{9} = -40.8417340899375$$
$$x_{10} = 25.1327412287183$$
$$x_{11} = -65.9734457253857$$
$$x_{12} = -53.4070751110265$$
$$x_{13} = -59.6902604182061$$
$$x_{14} = 74.5739798656666$$
$$x_{15} = -46.5524448088427$$
$$x_{16} = 18.8495559215388$$
$$x_{17} = 80.5118670544782$$
$$x_{18} = 63.6359781723457$$
$$x_{19} = 12.5663706143592$$
$$x_{20} = 56.5486677646163$$
$$x_{21} = -21.9911485751286$$
$$x_{22} = 6.28318530717959$$
$$x_{23} = -78.5398163397448$$
$$x_{24} = 37.6991118430775$$
$$x_{25} = -96.2124947519558$$
$$x_{26} = 21.9911485751286$$
$$x_{27} = -97.3893722612836$$
$$x_{28} = 100.530964914873$$
$$x_{29} = -47.1238898038469$$
$$x_{30} = 28.2743338823081$$
$$x_{31} = 94.2477796076938$$
$$x_{32} = -40.8407044966673$$
$$x_{33} = -34.5575191894877$$
$$x_{34} = -28.2743338823081$$
$$x_{35} = -85.4121130834002$$
$$x_{36} = -90.260314866971$$
$$x_{37} = -34.9842404193317$$
$$x_{38} = -79.4606661258204$$
$$x_{39} = 43.9822971502571$$
$$x_{40} = 75.398223686155$$
$$x_{41} = 62.8318530717959$$
$$x_{42} = -84.3813701398482$$
$$x_{43} = -3.14159265358979$$
$$x_{44} = 68.7396225684591$$
$$x_{45} = 87.9645943005142$$
$$x_{46} = -9.42477796076938$$
$$x_{47} = 31.4159265358979$$
$$x_{48} = 31.2527380956438$$
Signos de extremos en los puntos:
(-15.707963267948966, -1.50701727539007e-7)
(0, -1)
(-91.19986990414654, -4.04303150065854e-40)
(81.68140899333463, -3.35903709639911e-36)
(-72.25663103256524, -4.16240046723054e-32)
(-34.92947713867037, -1.06047627266875e-14)
(50.26548245743669, -1.47903461596179e-22)
(69.56062592329772, -8.45545260626203e-28)
(-40.84173408993747, -1.83280728040168e-18)
(25.132741228718345, -1.21615567094093e-11)
(-65.97344572538566, -2.22893071715432e-29)
(-53.40707511102649, -6.39148810034623e-24)
(-59.69026041820607, -1.19357379977897e-26)
(74.57397986566656, -4.86137607527994e-23)
(-46.55244480884272, -5.75158728239587e-18)
(18.84955592153876, -6.51241213607991e-9)
(80.51186705447822, -8.77942288424734e-15)
(63.63597817234566, -1.38045601340376e-19)
(12.566370614359172, -3.487342356209e-6)
(56.548667764616276, -2.76201244352236e-25)
(-21.991148575128552, -2.81426845748556e-10)
(6.283185307179586, -0.00186744273170799)
(-78.53981633974483, -7.77304449898755e-35)
(37.69911184307752, -4.24115118301608e-17)
(-96.21249475195584, -3.64447893646061e-17)
(21.991148575128552, -3553321280.84704)
(-97.3893722612836, -5.06212693294953e-43)
(100.53096491487338, -2.18754339521324e-44)
(-47.1238898038469, -3.42258854412123e-21)
(28.274333882308138, -1902773895292.16)
(94.2477796076938, -1.17141123423499e-41)
(-40.840704496667314, -1.83276760567157e-18)
(-34.55751918948773, -9.8143175935323e-16)
(-28.274333882308138, -5.25548517600645e-13)
(-85.41211308340019, -2.51221442358378e-31)
(-90.26031486697102, -4.81411641652805e-27)
(-34.984240419331734, -2.23213156812239e-14)
(-79.46066612582041, -2.90162212518714e-21)
(43.982297150257104, -7.92010695079813e-20)
(75.39822368615503, -1.79873633571987e-33)
(62.83185307179586, -5.15790006254285e-28)
(-84.3813701398482, -4.8309026479408e-34)
(-3.141592653589793, -0.0432139182637723)
(68.73962256845907, -1.1658553642877e-28)
(87.96459430051421, -6.27280941120808e-39)
(-9.42477796076938, -8.06995175703046e-5)
(31.41592653589793, -2.2711010683241e-14)
(31.25273809564381, -3.44251713837872e-14)
Intervalos de crecimiento y decrecimiento de la función:Hallemos los intervalos donde la función crece y decrece y también los puntos mínimos y máximos de la función, para lo cual miramos cómo se comporta la función en los extremos con desviación mínima del extremo:
Puntos mínimos de la función:
$$x_{1} = 21.9911485751286$$
$$x_{2} = 28.2743338823081$$
Puntos máximos de la función:
$$x_{2} = -15.707963267949$$
$$x_{2} = 81.6814089933346$$
$$x_{2} = -72.2566310325652$$
$$x_{2} = 50.2654824574367$$
$$x_{2} = 25.1327412287183$$
$$x_{2} = -65.9734457253857$$
$$x_{2} = -53.4070751110265$$
$$x_{2} = -59.6902604182061$$
$$x_{2} = 18.8495559215388$$
$$x_{2} = 12.5663706143592$$
$$x_{2} = 56.5486677646163$$
$$x_{2} = -21.9911485751286$$
$$x_{2} = 6.28318530717959$$
$$x_{2} = -78.5398163397448$$
$$x_{2} = 37.6991118430775$$
$$x_{2} = -97.3893722612836$$
$$x_{2} = 100.530964914873$$
$$x_{2} = -47.1238898038469$$
$$x_{2} = 94.2477796076938$$
$$x_{2} = -40.8407044966673$$
$$x_{2} = -34.5575191894877$$
$$x_{2} = -28.2743338823081$$
$$x_{2} = 43.9822971502571$$
$$x_{2} = 75.398223686155$$
$$x_{2} = 62.8318530717959$$
$$x_{2} = -3.14159265358979$$
$$x_{2} = 87.9645943005142$$
$$x_{2} = -9.42477796076938$$
$$x_{2} = 31.4159265358979$$
Decrece en los intervalos
$$\left[28.2743338823081, \infty\right)$$
Crece en los intervalos
$$\left(-\infty, 21.9911485751286\right]$$