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1、專題強(qiáng)化訓(xùn)練(四) (建議用時(shí):45分鐘)學(xué)業(yè)達(dá)標(biāo)練一、選擇題1cos 555的值為() 【導(dǎo)學(xué)號(hào):84352357】ABC DBcos 555cos(36018015)cos 15cos(4530).2sin cos(30)cos sin(30)等于()A BC DAsin cos(30)cos sin(30)sin(30)sin(30)sin 30.3已知,sin ,cos ,則等于() 【導(dǎo)學(xué)號(hào):84352358】A BCD或A,sin ,cos ,cos ,sin ,sin()sin cos cos sin ,又,.4函數(shù)ycos2sin21是()A最小正周期為2的奇函數(shù)B最小正周期為
2、的偶函數(shù)C最小正周期為的奇函數(shù)D最小正周期為2的偶函數(shù)Cy1coscossin 2x,f(x)是最小正周期為的奇函數(shù)5設(shè)函數(shù)f(x)cos2xsin xcos xa(其中0,aR)且f(x)的圖象在y軸右側(cè)的第一個(gè)最高點(diǎn)的橫坐標(biāo)是,則的值為() 【導(dǎo)學(xué)號(hào):84352359】A BC DAf(x)cos 2xsin 2xasina,依題意得2.二、填空題6已知函數(shù)f(x)sin(x)sincos2(x),則f_.f(x)sin xcos xcos2xsin 2xsin,fsincos.7若、為銳角,且滿足cos ,cos(),則sin _. 【導(dǎo)學(xué)號(hào):84352360】、為銳角,(0,)由cos
3、 ,求得sin ,由cos()求得sin(),sin sin()sin()cos cos()sin .8若2 018,則tan 2_.2 018tan 22 018.三、解答題9已知,sin .(1)求sin的值;(2)求cos的值. 【導(dǎo)學(xué)號(hào):84352361】解(1)因?yàn)?,sin ,所以cos .故sinsincos cossin .(2)由(1)知sin 22sin cos 2,cos 212sin2122,所以coscoscos 2sinsin 2.10已知函數(shù)f(x)sin x(2cos xsin x)cos2x.(1)求函數(shù)f(x)的最小正周期;(2)若,且f(),求sin 2的值
4、解(1)因?yàn)閒(x)sin x(2cos xsin x)cos2x,所以f(x)sin 2xsin2xcos2xsin 2xcos 2xsin,所以函數(shù)f(x)的最小正周期是.(2)f(),即sin,sin.因?yàn)?,所?,所以cos,所以sin 2sinsincos.沖A挑戰(zhàn)練1若(4tan 1)(14tan )17,則tan()等于()A2B3 C4D5C由已知得,4(tan tan )16(1tan tan ),即4,tan()4.2在ABC中,若B45,則cos Asin C的取值范圍是() 【導(dǎo)學(xué)號(hào):84352362】A1,1 BC DBB45,AC135,C135A,cos Asin
5、 Ccos Asin(135A)cos Acos2Asin Acos A(sin 2Acos 2A1)sin(2A45)1sin(2A45),0A135,452A45315,1sin(2A45)1,cos Asin C.3已知向量a(4,5cos ),b(3,4tan ),若ab,則cos_.因?yàn)閍b,所以435cos (4tan )0,解得sin .又因?yàn)椋詂os .cos 212sin2,sin 22sin cos ,于是coscos 2cossin 2sin.4函數(shù)f(x)的值域?yàn)開f(x)2sin x(1sin x)22,由1sin x0得1sin x1,所以f(x)的值域?yàn)?5已
6、知函數(shù)f(x)a(cos2xsin xcos x)b.(1)當(dāng)a0時(shí),求f(x)的單調(diào)遞增區(qū)間;(2)當(dāng)a0且x時(shí),f(x)的值域是3,4,求a,b的值. 【導(dǎo)學(xué)號(hào):84352363】解f(x)aasin 2xbsinb.(1)2k2x2k,kZ,kxk(kZ),即x,kZ,故f(x)的單調(diào)遞增區(qū)間為,kZ.(2)0x,2x,sin1,f(x)minab3,f(x)maxb4,a22,b4.6EDBC3191F2351DD815FF33D4435F3756EDBC3191F2351DD815FF33D4435F3756EDBC3191F2351DD815FF33D4435F3756EDBC3191F2351DD815FF33D4435F3756EDBC3191F2351DD815FF33D4435F3756EDBC3191F2351DD815FF33D4435F375