sin2x-cos2x怎么化成asin的形式
辅助角公式，提取系数平方和开根号，也就是二分之根号二绛旓細y= 3 sin2x-cos2x=2(3 2 sin2x- 1 2 cos2x)=2sin(2x- 蟺 6 )=2sin2(x- 蟺 12 )锛庢牴鎹乏鍔犲彸鍑忕殑鍘熷垯锛岃寰楀埌鍑芥暟y=2sin2x鐨勫浘璞″彧瑕佸皢y= 3 sin2x-cos2x鐨勫浘璞″悜宸﹀钩绉 蟺 12 涓崟浣
绛旓細绛旀锛歽=1/2sin4x 鍛愶紝涓轰簡鏂逛究锛屾垜浠笉濡ㄤ护2x=A 閭ｄ箞y=sinAcosA =1/2*2sinAcosA =1/2sin2A(涓よ灏嗗叕寮忥級=1/2sin4x 鍘勶紝鎳傚惁锛熸ゼ涓婂ソ鍍忛敊浜嗐
绛旓細cos2x-sin2x =鈭2*(cos2x*鈭2/2 - sin2x*鈭2/2)=鈭2*[cos2x*cos(蟺/4) - sin2x*sin(蟺/4)]=鈭2*cos(2x+ 蟺/4)
绛旓細=2cos2x+2sin2x =2鈭2sin(2x+蟺/4)瀹炲湪鐪嬩笉鎯竴缇ゅ娓ｇ鏅哄晢缁欎綘涔辫 濡傛灉浣犻棶鏈鍚庝竴姝ユ槸鎬庝箞鎺ㄥ嚭鏉ョ殑 璇疯繍鐢ㄦ櫤鍟嗘兂涓涓嬮珮涓瀛﹁繃鐨勪笁瑙掑嚱鏁拌緟鍔╄鍏紡 acosA+bsinA=鈭(a²+b²)sin(A+M) (tanM=a/b) 铏界劧杩欎釜鍏紡鍙兘鍦ㄩ珮涓敤涓嶈繃浣犲皢灏卞噾鍚堜竴涓嬨傛鐗堝叕寮忎负acosA+b...
绛旓細sin2x-cos2x-1 =鈭2(sin2x脳鈭2/2-cos2x脳鈭2/2)-1 =鈭2sin(2x-蟺/4)-1 濡傛灉鏈鏈変粈涔堜笉鏄庣櫧鍙互杩介棶锛屽鏋滄弧鎰忚寰楅噰绾 濡傛灉鏈夊叾浠栭棶棰樿閲囩撼鏈鍚庡彟鍙戠偣鍑诲悜鎴戞眰鍔╋紝绛旈涓嶆槗锛岃璋呰В锛岃阿璋傜瀛︿範杩涙
绛旓細sin2x-cos2x=0⇒sin2x=cos2x⇒tan2x=1锛坸鈮犗/2锛変负涓涓柟绋嬶紝鑻ョ湡鐨勬湁鍥惧儚鐨勮瘽锛屼篃璇ヤ负涓涓偣銆傦紙浣犳槸涓嶆槸瑕侀棶sin2x-cos2x=f锛坸锛夌殑鍥惧儚鎬庝箞鐢诲晩锛燂級
绛旓細鏍规嵁2鍊嶈鍏紡锛歴in(2x)=2sinxcosx y=sin2xcos2x=1/2(2sin2xcos2x)=1/2sin4x
绛旓細鐢卞嶈鍏紡锛cos2x=cos²x-sin²x 寰楋細y=cos²2x-sin²2x=cos4x 绁濅綘寮蹇冿紒甯屾湜鑳藉府鍒颁綘锛屽鏋滀笉鎳傦紝璇疯拷闂紝绁濆涔犺繘姝ワ紒O(鈭鈭)O
绛旓細鏈灏忔鍛ㄦ湡鏄銆倅=sin2x-cos2x=鈭2(鈭2/2*sin2x-鈭2/2cos2x)=鈭2(sin2xcos蟺/4-cos2xsin蟺/4)=鈭2sin(2x-蟺/4) 锛屾墍浠=2蟺/2=蟺銆傚鏋滀竴涓嚱鏁癴锛坸锛夌殑鎵鏈夊懆鏈熶腑瀛樺湪涓涓渶灏忕殑姝ｆ暟锛岄偅涔堣繖涓渶灏忕殑姝ｆ暟灏卞彨鍋歠锛坸锛夌殑鏈灏忔鍛ㄦ湡锛坢inimal positive period锛.渚嬪锛屾寮﹀嚱鏁...
