J^cos(x-生+ 0)为偶函数，则 0-— = k7rР4?4Р7TР:.0-k7i-\——,k e ZР4Р2 解：2(2cos25-1)-8cosB + 5 = 0,4cos25-8cos8 + 5 = 0Р得cos8 = —,sinB?-, cos0 =?£. = ,sin^ ,Р2?2 同.时 5?5Р4-3^3Рsin(B + 0) = sin B cos 0 + cos 8 sin 9 =————Р- h-n /冗?、/冗?、兀?,71?、?.?z 71?、?5Р3« 解：(?%) + (—F %) — —, cos(—F x) — sin(?x)——,Р4?4?2?4?4?13Р兀?兀?7T?71?120Р而 cos 2x = sin(— 一 2x) = sin 2(— -x) = 2 sin(— 一 x) cos(— -x) =-—Р120Рcos 2x _ 169 _ 12Р- =亏=后РCOS(?F X) —Р4?13Р.h-rj?z•/ \ 1 ♦ C?^[^€1 /'?C \?jР4 解：/ (]) = § q sin 2尤???(1 + cos 2x) H— q + bР=—sin 2x -?cos 2x + b = a sin(2x) + Z?Р2?2?3Р(1)?+ — < 2a:- — <?+ —,kn + — <x<k7i +Р2?3?2?12?12Р/. [k7i + ,k7i + e Z 为所求РР12?12РР兀?兀?兀?2勿?\13?兀Р(2) 0<.r<-, — —<2x —— <——，-—<sin(2x — —)<1Р2?3?3?3?2?3Р/(x)min =a + Z? = -2,y(x)max = a + b = ^3 ,Рa = 2Р& = -2 + V3РV3 ,.Р?a + b = -2Р2?nРa+b = y[3
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