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$$- 2 x \sin{\left(x \right)} \cos{\left(x \right)} + \cos^{2}{\left(x \right)} = 0$$
Resolvermos esta ecuaciónRaíces de esta ecuación
$$x_{1} = 1.5707963267949$$
$$x_{2} = 12.6060134442754$$
$$x_{3} = 14.1371669411541$$
$$x_{4} = -36.1283155162826$$
$$x_{5} = 7.85398163397448$$
$$x_{6} = 28.2920048800691$$
$$x_{7} = 42.4115008234622$$
$$x_{8} = -89.5353906273091$$
$$x_{9} = -67.5442420521806$$
$$x_{10} = -51.8362787842316$$
$$x_{11} = -83.2522053201295$$
$$x_{12} = 65.9810235167388$$
$$x_{13} = -14.1371669411541$$
$$x_{14} = 92.6769832808989$$
$$x_{15} = 64.4026493985908$$
$$x_{16} = 48.6946861306418$$
$$x_{17} = 67.5442420521806$$
$$x_{18} = -0.653271187094403$$
$$x_{19} = 23.5619449019235$$
$$x_{20} = 78.5461819355535$$
$$x_{21} = -65.9810235167388$$
$$x_{22} = -28.2920048800691$$
$$x_{23} = -80.1106126665397$$
$$x_{24} = 22.013857636623$$
$$x_{25} = -64.4026493985908$$
$$x_{26} = -29.845130209103$$
$$x_{27} = -75.4048544617952$$
$$x_{28} = -22.013857636623$$
$$x_{29} = -86.3937979737193$$
$$x_{30} = 4.71238898038469$$
$$x_{31} = -97.3945059759883$$
$$x_{32} = 20.4203522483337$$
$$x_{33} = -53.4164352526291$$
$$x_{34} = 6.36162039206566$$
$$x_{35} = -87.970277977177$$
$$x_{36} = -3.29231002128209$$
$$x_{37} = 50.2754273458806$$
$$x_{38} = -94.253084424113$$
$$x_{39} = -102.101761241668$$
$$x_{40} = -1.5707963267949$$
$$x_{41} = 86.3937979737193$$
$$x_{42} = -84.8288957966139$$
$$x_{43} = -12.6060134442754$$
$$x_{44} = 94.253084424113$$
$$x_{45} = 87.970277977177$$
$$x_{46} = -39.2699081698724$$
$$x_{47} = -43.9936619344429$$
$$x_{48} = 36.1283155162826$$
$$x_{49} = 51.8362787842316$$
$$x_{50} = 80.1106126665397$$
$$x_{51} = -50.2754273458806$$
$$x_{52} = 89.5353906273091$$
$$x_{53} = 58.1194640914112$$
$$x_{54} = 73.8274273593601$$
$$x_{55} = -58.1194640914112$$
$$x_{56} = -15.7397193560049$$
$$x_{57} = -6.36162039206566$$
$$x_{58} = -9.4774857054208$$
$$x_{59} = -72.26355003974$$
$$x_{60} = -20.4203522483337$$
$$x_{61} = 43.9936619344429$$
$$x_{62} = 29.845130209103$$
$$x_{63} = -95.8185759344887$$
$$x_{64} = -37.7123693157661$$
$$x_{65} = 26.7035375555132$$
$$x_{66} = -23.5619449019235$$
$$x_{67} = -42.4115008234622$$
$$x_{68} = 72.26355003974$$
$$x_{69} = 15.7397193560049$$
$$x_{70} = -81.6875298021918$$
$$x_{71} = -61.261056745001$$
$$x_{72} = 70.6858347057703$$
$$x_{73} = 100.535938219808$$
$$x_{74} = 34.5719807601687$$
$$x_{75} = 3.29231002128209$$
$$x_{76} = -59.6986356231676$$
$$x_{77} = -31.43183263459$$
$$x_{78} = 81.6875298021918$$
$$x_{79} = 59.6986356231676$$
$$x_{80} = 45.553093477052$$
$$x_{81} = -73.8274273593601$$
$$x_{82} = 56.5575080935408$$
$$x_{83} = 9.4774857054208$$
$$x_{84} = -45.553093477052$$
$$x_{85} = -7.85398163397448$$
$$x_{86} = -17.2787595947439$$
$$x_{87} = 37.7123693157661$$
$$x_{88} = 95.8185759344887$$
Signos de extremos en los puntos:
(1.5707963267948966, 5.8895428941999e-33)
(12.606013444275414, 12.5862127897398)
(14.137166941154069, 4.29347676987172e-30)
(-36.12831551628262, -3.66424875021481e-28)
(7.853981633974483, 7.36192861774987e-31)
(28.292004880069126, 28.2831712204135)
(42.411500823462205, 4.98859428281591e-28)
(-89.53539062730911, -2.60267852044683e-27)
(-67.54424205218055, -1.3132184568469e-27)
(-51.83627878423159, -3.09398107171563e-30)
(-83.25220532012952, -1.7964453843451e-28)
(65.9810235167388, 65.9772347661069)
(-14.137166941154069, -4.29347676987172e-30)
(92.6769832808989, 2.69152684487792e-27)
(64.40264939859077, 2.61429235475567e-27)
(48.6946861306418, 5.73178094238607e-28)
(67.54424205218055, 1.3132184568469e-27)
(-0.6532711870944031, -0.411949279841571)
(23.56194490192345, 1.73402701495236e-29)
(78.54618193555346, 78.5429992236281)
(-65.9810235167388, -65.9772347661069)
(-28.292004880069126, -28.2831712204135)
(-80.11061266653972, -1.92283264304371e-27)
(22.013857636622962, 22.002507009172)
(-64.40264939859077, -2.61429235475567e-27)
(-29.845130209103036, -1.12127665170554e-29)
(-75.40485446179518, -75.4015391711531)
(-22.013857636622962, -22.002507009172)
(-86.39379797371932, -3.32328051180095e-28)
(4.71238898038469, 1.59017658143397e-31)
(-97.39450597598831, -97.3919391637355)
(20.420352248333657, 1.96251734458305e-29)
(-53.41643525262913, -53.4117554551774)
(6.361620392065665, 6.32256349768101)
(-87.970277977177, -87.9674362000474)
(-3.2923100212820864, -3.21808738200779)
(50.27542734588058, 50.2704552295047)
(-94.25308442411298, -94.2504320656642)
(-102.10176124166829, -2.45314668072882e-27)
(-1.5707963267948966, -5.8895428941999e-33)
(86.39379797371932, 3.32328051180095e-28)
(-84.8288957966139, -84.8259487900249)
(-12.606013444275414, -12.5862127897398)
(94.25308442411298, 94.2504320656642)
(87.970277977177, 87.9674362000474)
(-39.269908169872416, -2.36773935254175e-30)
(-43.993661934442905, -43.9879800316228)
(36.12831551628262, 3.66424875021481e-28)
(51.83627878423159, 3.09398107171563e-30)
(80.11061266653972, 1.92283264304371e-27)
(-50.27542734588058, -50.2704552295047)
(89.53539062730911, 2.60267852044683e-27)
(58.119464091411174, 1.39112146798308e-29)
(73.82742735936014, 4.43565443427593e-28)
(-58.119464091411174, -1.39112146798308e-29)
(-15.73971935600487, -15.7238519846239)
(-6.361620392065665, -6.32256349768101)
(-9.477485705420795, -9.45118061522278)
(-72.26355003974, -72.260090646562)
(-20.420352248333657, -1.96251734458305e-29)
(43.993661934442905, 43.9879800316228)
(29.845130209103036, 1.12127665170554e-29)
(-95.81857593448869, -3.676520165044e-28)
(-37.712369315766125, -37.7057413561082)
(26.703537555513243, 1.44419018202913e-29)
(-23.56194490192345, -1.73402701495236e-29)
(-42.411500823462205, -4.98859428281591e-28)
(72.26355003974, 72.260090646562)
(15.73971935600487, 15.7238519846239)
(-81.6875298021918, -81.6844694741999)
(-61.26105674500097, -5.29879683037424e-28)
(70.68583470577035, 6.77618297499812e-29)
(100.53593821980844, 100.533451608344)
(34.57198076016866, 34.564750982936)
(3.2923100212820864, 3.21808738200779)
(-59.698635623167625, -59.6944482165077)
(-31.431832634590037, -31.4238809266115)
(81.6875298021918, 81.6844694741999)
(59.698635623167625, 59.6944482165077)
(45.553093477052, 1.74530768724744e-35)
(-73.82742735936014, -4.43565443427593e-28)
(56.55750809354077, 56.5530881593697)
(9.477485705420795, 9.45118061522278)
(-45.553093477052, -1.74530768724744e-35)
(-7.853981633974483, -7.36192861774987e-31)
(-17.278759594743864, -2.10139136502906e-29)
(37.712369315766125, 37.7057413561082)
(95.81857593448869, 3.676520165044e-28)
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:
$$x_{1} = 1.5707963267949$$
$$x_{2} = 14.1371669411541$$
$$x_{3} = 7.85398163397448$$
$$x_{4} = 42.4115008234622$$
$$x_{5} = 92.6769832808989$$
$$x_{6} = 64.4026493985908$$
$$x_{7} = 48.6946861306418$$
$$x_{8} = 67.5442420521806$$
$$x_{9} = -0.653271187094403$$
$$x_{10} = 23.5619449019235$$
$$x_{11} = -65.9810235167388$$
$$x_{12} = -28.2920048800691$$
$$x_{13} = -75.4048544617952$$
$$x_{14} = -22.013857636623$$
$$x_{15} = 4.71238898038469$$
$$x_{16} = -97.3945059759883$$
$$x_{17} = 20.4203522483337$$
$$x_{18} = -53.4164352526291$$
$$x_{19} = -87.970277977177$$
$$x_{20} = -3.29231002128209$$
$$x_{21} = -94.253084424113$$
$$x_{22} = 86.3937979737193$$
$$x_{23} = -84.8288957966139$$
$$x_{24} = -12.6060134442754$$
$$x_{25} = -43.9936619344429$$
$$x_{26} = 36.1283155162826$$
$$x_{27} = 51.8362787842316$$
$$x_{28} = 80.1106126665397$$
$$x_{29} = -50.2754273458806$$
$$x_{30} = 89.5353906273091$$
$$x_{31} = 58.1194640914112$$
$$x_{32} = 73.8274273593601$$
$$x_{33} = -15.7397193560049$$
$$x_{34} = -6.36162039206566$$
$$x_{35} = -9.4774857054208$$
$$x_{36} = -72.26355003974$$
$$x_{37} = 29.845130209103$$
$$x_{38} = -37.7123693157661$$
$$x_{39} = 26.7035375555132$$
$$x_{40} = -81.6875298021918$$
$$x_{41} = 70.6858347057703$$
$$x_{42} = -59.6986356231676$$
$$x_{43} = -31.43183263459$$
$$x_{44} = 45.553093477052$$
$$x_{45} = 95.8185759344887$$
Puntos máximos de la función:
$$x_{45} = 12.6060134442754$$
$$x_{45} = -36.1283155162826$$
$$x_{45} = 28.2920048800691$$
$$x_{45} = -89.5353906273091$$
$$x_{45} = -67.5442420521806$$
$$x_{45} = -51.8362787842316$$
$$x_{45} = -83.2522053201295$$
$$x_{45} = 65.9810235167388$$
$$x_{45} = -14.1371669411541$$
$$x_{45} = 78.5461819355535$$
$$x_{45} = -80.1106126665397$$
$$x_{45} = 22.013857636623$$
$$x_{45} = -64.4026493985908$$
$$x_{45} = -29.845130209103$$
$$x_{45} = -86.3937979737193$$
$$x_{45} = 6.36162039206566$$
$$x_{45} = 50.2754273458806$$
$$x_{45} = -102.101761241668$$
$$x_{45} = -1.5707963267949$$
$$x_{45} = 94.253084424113$$
$$x_{45} = 87.970277977177$$
$$x_{45} = -39.2699081698724$$
$$x_{45} = -58.1194640914112$$
$$x_{45} = -20.4203522483337$$
$$x_{45} = 43.9936619344429$$
$$x_{45} = -95.8185759344887$$
$$x_{45} = -23.5619449019235$$
$$x_{45} = -42.4115008234622$$
$$x_{45} = 72.26355003974$$
$$x_{45} = 15.7397193560049$$
$$x_{45} = -61.261056745001$$
$$x_{45} = 100.535938219808$$
$$x_{45} = 34.5719807601687$$
$$x_{45} = 3.29231002128209$$
$$x_{45} = 81.6875298021918$$
$$x_{45} = 59.6986356231676$$
$$x_{45} = -73.8274273593601$$
$$x_{45} = 56.5575080935408$$
$$x_{45} = 9.4774857054208$$
$$x_{45} = -45.553093477052$$
$$x_{45} = -7.85398163397448$$
$$x_{45} = -17.2787595947439$$
$$x_{45} = 37.7123693157661$$
Decrece en los intervalos
$$\left[95.8185759344887, \infty\right)$$
Crece en los intervalos
$$\left(-\infty, -97.3945059759883\right]$$