sin2x等于什么呢？
sin2x等于2sinxcosx。这其实是由两角和的正弦公式sin(x+y)=sinxcosy+cosxsiny得到。此外，还有几个三角恒等式cos(x+y)=cosxcosy-sinxsinycos(x-y)=cosxcosy+sinxsinysin(x-y)=sinxcosy-cosxsinytan(x+y)=(tanx+tany)/(1-tanxtany)tan(x-y)=(tanx-tany)/(1+tanxtany)想推导出各种二倍角公式，只需将和角公式中的y替换为x即可。
sin2x的取值范围
函数y=sin2x是正弦函数，它的自变量的取值范围是全体实数，它的值域是-1到1，它的导函数应区分外层与内层函数分别求导尔后求积。那么我们知道，它的外层函数的导数是cos2x，它的内层函数是2x，它的导数是2，那么原函数的导数就是等于2cos2x。
绛旓細sin2x=2sinxcosx銆傚垎鏋愯繃绋嬪涓嬶細sin(伪+尾)=sin伪cos尾+ sin尾cos伪 sin(伪-尾)=sin伪cos尾-sinB*cos伪 鏍规嵁sin(伪+尾)=sin伪cos尾+ sin尾cos伪鍙緱锛歴in2x=sin锛坸+x锛=sinxcosx+sinxcosx=2sinxcosx 甯哥敤鍏紡锛氬叕寮忎竴锛氳伪涓轰换鎰忚锛岀粓杈圭浉鍚岀殑瑙掔殑鍚屼竴涓夎鍑芥暟鐨勫肩浉绛夛細sin锛2k蟺+...
绛旓細sin2x=2sinxcosx銆傚垎鏋愯繃绋嬪涓嬶細sin(伪+尾)=sin伪cos尾+ sin尾cos伪 sin(伪-尾)=sin伪cos尾-sinB*cos伪 鏍规嵁sin(伪+尾)=sin伪cos尾+ sin尾cos伪鍙緱锛歴in2x=sin锛坸+x锛=sinxcosx+sinxcosx=2sinxcosx
绛旓細sin2x绛変簬2sinxcosx銆傝繖鍏跺疄鏄敱涓よ鍜岀殑姝ｅ鸡鍏紡sin(x+y)=sinxcosy+cosxsiny寰楀埌銆傛澶栵紝杩樻湁鍑犱釜涓夎鎭掔瓑寮廲os(x+y)=cosxcosy-sinxsinycos(x-y)=cosxcosy+sinxsinysin(x-y)=sinxcosy-cosxsinytan(x+y)=(tanx+tany)/(1-tanxtany)tan(x-y)=(tanx-tany)/(1+tanxtany)鎯虫帹瀵煎嚭鍚勭浜屽...
绛旓細sin2x=2sinxcosx.甯屾湜閲囩撼鈥︹﹁阿璋⑩︹﹀涔犺繘姝モ︹
绛旓細=2sinxcosx 杩欐槸涓叕寮,璇佹槑濡備笅 sin2x=sin锛坸+x)=sinxcosx+sinxcosx =2sinxcosx
绛旓細杩欏叾瀹炴槸鐢变袱瑙掑拰鐨勬寮﹀叕寮忥紝鐢眘in (xty)=sinxcosy+cosxsiny寰楀埌锛屾墍浠in2x绛変簬2sinxcosx銆傚湪璁＄畻涓彲浠ョ敤鏉ュ寲绠璁＄畻寮忋佸噺灏戞眰涓夎鍑芥暟鐨勬鏁帮紝鍦ㄥ伐绋嬩腑涔熸湁骞挎硾鐨勮繍鐢紝璇ュ叕寮忔槸涓夎鍑芥暟涓潪甯稿疄鐢ㄧ殑涓绫诲叕寮忋傚嶈鍏紡锛屾槸涓夎鍑芥暟涓潪甯稿疄鐢ㄧ殑涓绫诲叕寮忋傚氨鏄妸浜屽嶈鐨勪笁瑙掑嚱鏁扮敤鏈鐨勪笁瑙掑嚱鏁拌〃绀...
绛旓細sinx涔榗osx=(1/2)sin2x銆傝绠楄繃绋嬪涓嬶細2sinxcosx =sin2xsinxcosx =1/2sin2x 绉殑鍏崇郴锛歴in伪 = tan伪 脳 cos伪锛堝嵆sin伪 / cos伪 = tan伪 锛塩os伪 = cot伪 脳 sin伪 锛堝嵆cos伪 / sin伪 = cot伪锛塼an伪 = sin伪 脳 sec伪 (鍗 tan伪 / sin伪 = sec伪)鐩稿叧淇℃伅锛氬父瑙佺殑涓夎...
绛旓細sin2x=2sinxcosx锛岃繖涓叕寮忓湪涓夎鍑芥暟閲岄潰琚О涓轰簩鍊嶈鍏紡銆傚畠鐨勮瘉鏄庢柟娉曟槸鍒嗗埆鏍规嵁sin锛坅+b锛=sinacosb+cosasinb锛宑os锛坅+b锛=cosasinb-sinacosb浠ｅ叆涓や釜鐩稿悓鐨勬湭鐭ラ噺x鎺ㄦ潵鐨勩傚叧浜巗in锛坅+b锛=sinacosb+cosasinb鐨勮瘉鏄庯紝涓鑸殑鏂规硶鏄敾涓涓崟浣嶅渾锛屽涓嬪浘鎵绀猴紝鍒嗗埆浣滃嚭伪锛屛诧紝瑙扐OD鍗充负涓よ...
绛旓細杩鏄涓叕寮忥紝缁忓父鐢ㄧ殑锛岃璁颁綇銆sin2x =sin锛坸+x)=sinxcosx+sinxcosx =2sin2xcos2x 姝ｇ‘婊℃剰璇锋偍閲囩撼锛岃阿璋紒
绛旓細1銆乻in2x=2sinxcosx銆傝繖鍏跺疄鏄敱涓よ鍜岀殑姝ｅ鸡鍏紡锛岀敱sin锛坸+y锛=sinxcosy+cosxsiny 寰楀埌銆2銆佹澶,杩樻湁鍑犱釜涓夎鎭掔瓑寮忥細cos锛坸-y锛=cosxcosy+sinxsiny銆俿in锛坸-y锛=sinxcosy-cosxsiny?锛屾兂鎺ㄥ鍑哄悇绉嶄簩鍊嶈鍏紡锛屽彧闇灏嗗拰瑙掑叕寮忎腑鐨剏鏇挎崲涓簒鍗冲彲銆3銆佹敞鎰忥細涓よ鍜屽樊鐨勬鍒囧叕寮忓繀椤诲湪绛夊紡涓よ竟...
