2、”46[导学号21500531]C-D-8.已知sin2a=2-2cos2a,则tana=9•函数/(x)=sin2xsin^-cos2xcosy在■号,另上的单调递增区I'可为~5tt10.在"BC中,C=60°,tan^+tan^=l,则tan^tan^=11.已知afi均为锐角,且sina=
3、,tan(«-/?)=-
4、.⑴求sin(a-/5)的值;(2)求cos0的值.综合提升组12.(2017T西名校联考,理9)已知LABC的面积为S,且丽•AC=S,则tan2A的值为()A4-3-D10.(2017河北衡水中学三调
5、,理3)若炸(号,tc),且3cos2a=sinQ-aj,则sin2a的值为()C-S17D-i811.(2017河北邯郸二模,理5)已知3sin2&=4tan0,且洋加伙WZ),则cos2&等于()1-3A1-3B1-4■c1-4D
6、[导学号21500532]10.函数/(x)=4cos2
7、cosQ-x^-2sinx-
8、In(x+l)
9、的零点个数为.创新应用组16•设q=cos50°cos127°+cos40°cos37°,/?=—(sin56°-cos56°),cl-tan239°l+tan239°^则的大小关系是()
10、.a>b>cB.b>a>cC.c>a>bD.a>c>b[[导学号21500533]17.己知sin(0+》=詁e则cos(&+鲁)的值为参考答案课时规范练21两角和与差的正弦、余弦与正切公式1.Dcos2x=2cos2x-1=2x(^)-1=i2.Dcos70°sin50°-cos200°sin40°=cos70°sin50°+cos20°sin40°=cos70°sin50°+sin70°cos50°=sin(50o+70°)=sm120。=亍3.B因为aW(it,乎),且cos所以sin所以tana=-.44所以吨呵=益
11、诗弓4.Asin2&=・cos(中+20)=2sin2Q+0)・15.C因为tana=2tan-,5所以cos(《零)sin(a・£)sintana+tan^Atana-tan^n3tan^^=3IT丿・tan-(吩)sin(a+£)sin足)sinacos£+cosasin£sinacos^-cosasin^6.CScos(a・三)+sina=—cosa+-sina=—.6/225・:icOSG+逼Six」225=-(?sina+lcosa)4且tanx=3tan^rx-^^:tan(r)=tanx-tany1+tanx
12、tany2tanyl+3tan12y2一西■71<—=tan-,-——+3tany36tany丿当且仅当3tan2y=l时取等号,・:兀-尹的最大值为£故选B68.0或扌:’已知sin2a=2-2cos2a=2-2(l-2sin2a)=4sin2a,•:2sinacosa=4sin%M-5^1•:sina=0,或cosa=2sina,艮卩tana=0,或tana=
13、./(x)=sin2xsin--cos2rcos—=sin2xsin-+cos2xcos-=cos(2x--46666/当2k7i-n<2x^<2kTi(kZ)
14、,6即Zr7t-
15、^16、锐角,且sin«=
17、,•4•・cosa=-5•:cos"=cos[«-(«-/?)]=cosacos(a-0)+sinix^+£x/J10A=9^051051075012.D设△/EC的角A,B,C所对应的边分别为a,b,c.VAB-AC=S,•:hccosA=-/?csinA,•:ta