我知道sin平方x=2sinxcosx那么cos平方x等于什么啊？ 已知函数y=2sinxcosx-sin平方x+cos平方x(...
\u8c01\u80fd\u89e3\u7b54\u4e00\u4e0bcos\u5e73\u65b9x\u2014sin\u5e73\u65b9x\u7b49\u4e8e\u4ec0\u4e48\uff1f\u8fd8\u67092sinxcosx\u7b49\u4e8e\u4ec0\u4e48\uff1f\u8fd8\u6709\u7ed9\u6211\u4e00\u4e0b\u7b2c\u4e8c\u6b65cos2x=cos^2x-sin^2x
sin2x=2sinxcosx
\u56e0\u4e3asin45=cos45=\u221a2/2\u8fd9\u662f\u4e09\u89d2\u51fd\u6570\u5e38\u7528\u7684\u7b80\u5316\u89d2\u5ea6\u3002
\u65e2\u7136\u4e58\u4e86=\u221a2/2\u3002\u6240\u4ee5\u5c31\u8981\u4e58\u4ee5=\u221a2\u3002
\u524d\u9762\u4e00\u9879\u662fsin2x\uff0c\u540e\u9762\u4e24\u9879\u662fcos2x\uff0c\u518d\u5408\u5e76\u3002\u4e3a\u6839\u53f72*sin\uff082x+45\uff09
sin的平方不等于2sinxcosxsin（2x）=2sinxcosx
cos的平方=1-（sin的平方）
sin^2x=2sinxcosx
cos^2x=1-sin^2x=1-2sinxcosx.
sin2x=2sinxcosx
cos2x=(cosx^)2-(sinx)^2
绛旓細sin骞虫柟x鐨勫鏁板彲浠ュ啓鎴愶細锛坰in²x锛'=2sinx锛坰inx锛'=2sinxcosx=sin2x銆俿inx骞虫柟锛歽=sinx^2锛寉'=cosx^2*2x=2xcosx^2 瀵兼暟鏄嚱鏁板浘鍍忓湪鏌愪竴鐐瑰鐨勬枩鐜囷紝涔熷氨鏄旱鍧愭爣澧為噺锛埼攜锛夊拰妯潗鏍囧閲忥紙螖x锛夊湪螖x-->0鏃剁殑姣斿笺傚井鍒嗘槸鎸囧嚱鏁板浘鍍忓湪鏌愪竴鐐瑰鐨勫垏绾垮湪妯潗鏍囧彇寰楀閲徫攛浠ュ悗锛...
绛旓細sin锛2x锛=2sinxcosx cos鐨骞虫柟=1-锛坰in鐨勫钩鏂癸級
绛旓細1.(sin²x)' = 2sinx(sinx)' = 2sinxcosx = sin2x銆2.(sin²x)' = [(1-cos2x)/2]' = [1/2 - (cos2x)/2]' = 0 - ½(-sin2x)(2x)' = ½(sin2x)脳2 = sin2x銆
绛旓細鍙樹笉浜2sinx
绛旓細sin鐨骞虫柟涔熷氨鏄痵in²x锛宻in²x澶т簬绛変簬0锛岀浉搴旂殑绛夊紡鏈夛細sin²x=(1-cos2x)/2锛泂in²x=[1-cos锛2x锛塢/2锛泂in²x+cos²x=1锛(sin²x)'=2sinx(sinx)'=2sinxcosx=sin2x锛(sin²x)'=[(1-cos2x)/2]'=[1/2-(cos2x)/2]'=0-½...
绛旓細杩欎釜鏄簩鍊嶈鍏紡锛歴in2x=2sinxcosx tan2x=2tanx/(1-(tanx)^2)cos2x=(cosx)^2-(sinx)^2=2(cosx)^2-1=1-2(sinx)^2 鍊嶈鍏紡 鍊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〃绀哄嚭鏉ャ傚湪璁＄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...
绛旓細鎺ㄥ杩囩▼锛歝os2X銆=(cosX)^2-(sinX)^2銆=2*(cosX)^2-1銆=1-2*(sinX)^2銆傚悓瑙掍笁瑙掑嚱鏁扮殑鍩烘湰鍏崇郴寮忥細鍊掓暟鍏崇郴锛歵an伪路cot伪锛1銆乻in伪路csc伪锛1銆乧os伪路sec伪锛1銆傚晢鐨勫叧绯伙細sin伪锛廲os伪锛漷an伪锛漵ec伪锛廲sc伪銆乧os伪锛弒in伪锛漜ot伪锛漜sc伪锛弒ec伪銆傚拰鐨勫叧绯伙細sin2伪锛媍os2伪...
绛旓細杩欎釜鏄釜澶嶅悎鍑芥暟鐨勬眰瀵笺備綘鍙互鍏堟妸sinx鐪嬫垚涓涓暣浣擄紝鎸夋眰瀵肩殑鍏紡锛屽彲浠ユ眰鍑 y'=2sinx锛屼絾 sinx鍘熸湰涔熸槸涓嚱鏁帮紝杩欏氨闇瑕佸啀瀵硅繖涓湰浣撳嚱鏁拌繘琛屾眰瀵硷紝鍥犳 y'=2sinx*(sinx)'=2sinxcosx = sin2X
绛旓細sin²x =(sinx)²=2sinx(sinx)'=2sinxcosx =sin2x 鍑芥暟鍙鐨勬潯浠讹細濡傛灉涓涓嚱鏁扮殑瀹氫箟鍩熶负鍏ㄤ綋瀹炴暟锛屽嵆鍑芥暟鍦ㄥ叾涓婇兘鏈夊畾涔夈傚嚱鏁板湪瀹氫箟鍩熶腑涓鐐瑰彲瀵奸渶瑕佷竴瀹氱殑鏉′欢锛氬嚱鏁板湪璇ョ偣鐨勫乏鍙冲鏁板瓨鍦ㄤ笖鐩哥瓑锛屼笉鑳借瘉鏄庤繖鐐瑰鏁板瓨鍦ㄣ傚彧鏈夊乏鍙冲鏁板瓨鍦ㄤ笖鐩哥瓑锛屽苟涓斿湪璇ョ偣杩炵画锛屾墠鑳借瘉鏄庤鐐瑰彲瀵笺
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...
