1、双基限时练(三十一)基 础 强 化1cos75cos15的值为()A. BC. D解析cos75cos152sin45sin30.答案D2cos37.5cos22.5的值是()A. B.C.() D.()解析cos37.5cos22.5(cos60cos15).答案D3.的值为()A. B.C. D解析原式.答案D4sin20cos70sin10sin50的值为()A. B.C. D.解析原式cos60cos(40).答案A5cos20cos60cos100cos140的值为()A B.C. D.解析原式(cos20cos100)cos402cos60cos40cos40cos40cos40.
2、答案B6.的化简结果为()Atan Btan2Ccot Dcot2解析tan2.答案B7sin10sin50sin70_.解析原式2sin30cos20cos20cos20cos200.答案08函数ysinsinx的最大值为_解析ycos.y的最大值为.答案能 力 提 升9化简sin220cos280sin20cos80_.解析原式(sin100sin60)1(cos40cos20)1cos30cos10cos101.答案10求值cos40cos80cos80cos160cos40cos160.解析原式cos80(cos40cos160)cos(16040)cos(16040)2cos80co
3、s100cos60cos200cos80cos100cos20(cos180cos20)cos20cos20cos20.11已知sinsinsinsin,求证:21.证明sinsinsinsin,2sincoscos()cos()4sincos2.cos22cossinsin21.21.12求函数f(x)sinx的最小正周期与最小值解析f(x)sinsinx2cossinsinxcossin.函数f(x)的最小正周期为,f(x)的最大值为,最小值为.能 力 提 升13若cosxcosysinxsiny,sin2xsin2y,则sin(xy)_.解析依题意,得cos(xy),2sin(xy)cos(xy),sin(xy).答案