cos2x等于多少
根据二倍角公式，cos2x=cos²x-sin²x=1-2sin²x=2cos²x
1-cos2x=1-（1-2cos²x）=2cos²x
绛旓細cos2x=1-2sinx鐨勫钩鏂广傛紨绠楄繃绋嬪涓嬶細cos2x=cos?x-sin?x=2cos?x-1=1-2sin?x=(1-tan?x)/(1+tan?x)锛屽嵆cos2x=1-2sinx鐨勫钩鏂广俢os鍗充綑寮︼紝鏄笁瑙掑嚱鏁扮殑涓绉嶏紝甯歌鐨勪笁瑙掑嚱鏁拌繕鏈夋寮in鍜屾鍒噒an銆
绛旓細涓夎鍑芥暟浠ｆ崲锛cos2X=(cosX)^2-(sinX)^2=2*(cosX)^2-1=1-2*(sinX)^2 鍗筹細cos2x=2cosx鐨勫钩鏂-1=cosx鐨勫钩鏂-sinx骞虫柟=1-2sinx鐨勫钩鏂 鍊掓暟鍏崇郴锛氣憼 锛涒憽 锛涒憿 鍟嗘暟鍏崇郴锛氣憼 锛涒憽 锛庡钩鏂瑰叧绯伙細鈶 锛涒憽 锛涒憿
绛旓細x绛変簬3/8蟺锛cos2x=cos锛3蟺/4锛=-锛堚垰2锛/2銆
绛旓細cos2x绛変簬澶氬皯 1銆乧os2x=cos2x-sin2x=2cos2x-1=1-2sin2x=(1-tan2x)/(1+tan2x)2銆乲脳蟺/2卤a(k鈭坺)鐨勪笁瑙掑嚱鏁板煎綋k涓哄伓鏁版椂锛岀瓑浜幬辩殑鍚屽悕涓夎鍑芥暟鍊硷紝鍓嶉潰鍔犱笂涓涓妸伪鐪嬩綔閿愯鏃跺師涓夎鍑芥暟鍊肩殑绗﹀彿锛涘綋k涓哄鏁版椂锛岀瓑浜幬辩殑寮傚悕涓夎鍑芥暟鍊硷紝鍓嶉潰鍔犱笂涓涓妸伪鐪嬩綔閿愯鏃跺師涓夎鍑芥暟鍊...
绛旓細cos2x璇佹槑杩囩▼ cos2x=cos²x-sin²x =2cos²x-1 =1-2sin²x =(1-tan²x)/(1+tan²x)k脳蟺/2卤a(k鈭坺)鐨勪笁瑙掑嚱鏁板硷紝褰搆涓哄伓鏁版椂锛绛変簬伪鐨勫悓鍚嶄笁瑙掑嚱鏁板硷紝鍓嶉潰鍔犱笂涓涓妸伪鐪嬩綔閿愯鏃跺師涓夎鍑芥暟鍊肩殑绗﹀彿锛屽綋k涓哄鏁版椂锛岀瓑浜幬辩殑寮傚悕涓夎鍑芥暟鍊硷紝...
绛旓細灏哻os²x鍜宻in²x浠ｅ叆涓婂紡锛屽緱鍒帮細cos2x鍦ㄦ暟瀛︿腑鏈夊緢澶氬簲鐢紝渚嬪鍦ㄤ笁瑙掑嚱鏁扮殑璁＄畻涓紝鎴栬呭湪鐗╃悊瀛︺佸伐绋嬪绛夐鍩熶腑鐨勫簲鐢ㄣ傛垜浠彲浠ラ氳繃浠ヤ笅鍏紡鏉ユ帹瀵糲os2x鐨勫硷細cos2x鏄暟瀛︿腑甯歌鐨勪笁瑙掑嚱鏁帮紝瀹冪殑鍊煎彲浠ラ氳繃涓浜涘熀鏈叕寮忔潵姹傝В銆傚湪鏈枃涓紝鎴戜滑灏嗚缁嗚В鏋恈os2x鐨勫煎強鐩稿叧鍏紡锛屼互渚胯鑰...
绛旓細鐩存帴鐢ㄥ弽涓夎鍑芥暟 cosx=1/2 arccos1/2=60掳 x=60掳锛2x=120掳 cos120掳=-1/2 鐢ㄤ簩鍊嶈鍏紡锛cos2x=2cos²x-1=1/2-1=-1/2 鏈涢噰绾冲挴锛
绛旓細Cos2x=cos(x+x)=cosx*cosx--sinxsinx
绛旓細1.cos鏂x绛変簬1-sin2x锛cos2x=(cos2x+1)/2锛宑os2x=cos2x+sin2x锛宑os2x=sin2x/tan2x銆2.涓夎鍑芥暟鏄暟瀛︿腑灞炰簬鍒濈瓑鍑芥暟涓殑瓒呰秺鍑芥暟鐨勫嚱鏁般3.瀹冧滑鐨勬湰璐ㄦ槸浠讳綍瑙掔殑闆嗗悎鍜屼竴涓瘮鍊肩殑闆嗗悎鐨勫彉閲忎箣闂寸殑鏄犲皠銆4.閫氬父鐨勪笁瑙掑嚱鏁版槸鍦ㄥ钩闈㈢洿瑙掑潗鏍囩郴涓畾涔夌殑銆5.鍏跺畾涔夊煙涓烘暣涓疄鏁板煙銆6.鍙︿竴绉嶅畾涔...
绛旓細cos2x绛変簬澶氬皯 cos2x绛変簬澶氬皯... cos2x绛変簬澶氬皯 灞曞紑 鎴戞潵绛 1涓洖绛 #鐑# 缃戞枃璐ㄩ噺鏄笉鏄笅闄嶄簡?lyp972005 2018-01-08 路 TA鑾峰緱瓒呰繃1260涓禐 鐭ラ亾灏忔湁寤烘爲绛斾富 鍥炵瓟閲:858 閲囩撼鐜:84% 甯姪鐨勪汉:175涓 鎴戜篃鍘荤瓟棰樿闂釜浜洪〉 鍏虫敞 灞曞紑鍏ㄩ儴 宸茶禐杩 宸茶俯杩< 浣犲杩欎釜鍥炵瓟鐨勮瘎浠...
