cos2x等于什么 cos2x等于什么？
Cos2x\u7b49\u4e8e\u4ec0\u4e48\uff1f\u4e09\u89d2\u51fd\u6570\u4ee3\u6362\uff1a
cos2X=(cosX)^2-(sinX)^2=2*(cosX)^2-1=1-2*(sinX)^2
\u5373\uff1acos2x=2cosx\u7684\u5e73\u65b9-1=cosx\u7684\u5e73\u65b9-sinx\u5e73\u65b9=1-2sinx\u7684\u5e73\u65b9
cos2x\u7684\u51fd\u6570\u56fe\u50cf:
\u6269\u5c55\u8d44\u6599\uff1a
\u5e38\u7528\u516c\u5f0f\uff1a
\u516c\u5f0f\u4e00\uff1a
\u8bbe\u03b1\u4e3a\u4efb\u610f\u89d2\uff0c\u7ec8\u8fb9\u76f8\u540c\u7684\u89d2\u7684\u540c\u4e00\u4e09\u89d2\u51fd\u6570\u7684\u503c\u76f8\u7b49\uff1a
sin\uff082k\u03c0+\u03b1\uff09=sin\u03b1 \uff08k\u2208Z\uff09
cos\uff082k\u03c0+\u03b1\uff09=cos\u03b1 \uff08k\u2208Z\uff09
tan\uff082k\u03c0+\u03b1\uff09=tan\u03b1 \uff08k\u2208Z\uff09
cot\uff082k\u03c0+\u03b1\uff09=cot\u03b1\uff08k\u2208Z\uff09
\u516c\u5f0f\u4e8c\uff1a
\u8bbe\u03b1\u4e3a\u4efb\u610f\u89d2\uff0c\u03c0+\u03b1\u7684\u4e09\u89d2\u51fd\u6570\u503c\u4e0e\u03b1\u7684\u4e09\u89d2\u51fd\u6570\u503c\u4e4b\u95f4\u7684\u5173\u7cfb\uff1a
sin\uff08\u03c0+\u03b1\uff09= \uff0dsin\u03b1
cos\uff08\u03c0+\u03b1\uff09=\uff0dcos\u03b1
tan\uff08\u03c0+\u03b1\uff09= tan\u03b1
cot\uff08\u03c0+\u03b1\uff09=cot\u03b1
\u516c\u5f0f\u4e09\uff1a
\u4efb\u610f\u89d2\u03b1\u4e0e-\u03b1\u7684\u4e09\u89d2\u51fd\u6570\u503c\u4e4b\u95f4\u7684\u5173\u7cfb\uff08\u5229\u7528 \u539f\u51fd\u6570 \u5947\u5076\u6027\uff09\uff1a
sin\uff08\uff0d\u03b1\uff09=\uff0dsin\u03b1
cos\uff08\uff0d\u03b1\uff09= cos\u03b1
tan\uff08\uff0d\u03b1\uff09=\uff0dtan\u03b1
\u516c\u5f0f\u56db\uff1a
\u5229\u7528\u516c\u5f0f\u4e8c\u548c\u516c\u5f0f\u4e09\u53ef\u4ee5\u5f97\u5230\u03c0-\u03b1\u4e0e\u03b1\u7684\u4e09\u89d2\u51fd\u6570\u503c\u4e4b\u95f4\u7684\u5173\u7cfb\uff1a
sin\uff08\u03c0\uff0d\u03b1\uff09= sin\u03b1
cos\uff08\u03c0\uff0d\u03b1\uff09=\uff0dcos\u03b1
tan\uff08\u03c0\uff0d\u03b1\uff09=\uff0dtan\u03b1
cot\uff08\u03c0\uff0d\u03b1\uff09=\uff0dcot\u03b1
\u516c\u5f0f\u4e94\uff1a
\u5229\u7528\u516c\u5f0f\u4e00\u548c\u516c\u5f0f\u4e09\u53ef\u4ee5\u5f97\u52302\u03c0-\u03b1\u4e0e\u03b1\u7684\u4e09\u89d2\u51fd\u6570\u503c\u4e4b\u95f4\u7684\u5173\u7cfb\uff1a
sin\uff082\u03c0-\u03b1\uff09= \uff0dsin\u03b1
cos\uff082\u03c0-\u03b1\uff09= cos\u03b1
tan\uff082\u03c0-\u03b1\uff09=\uff0dtan\u03b1
cot\uff082\u03c0-\u03b1\uff09=\uff0dcot\u03b1
\u516c\u5f0f\u516d\uff1a
\u03c0/2\u00b1\u03b1\u4e0e\u03b1\u7684\u4e09\u89d2\u51fd\u6570\u503c\u4e4b\u95f4\u7684\u5173\u7cfb\uff1a
sin\uff08\u03c0/2+\u03b1\uff09=cos\u03b1
sin\uff08\u03c0/2\uff0d\u03b1\uff09=cos\u03b1
cos\uff08\u03c0/2+\u03b1\uff09=\uff0dsin\u03b1
cos\uff08\u03c0/2\uff0d\u03b1\uff09=sin\u03b1
tan\uff08\u03c0/2+\u03b1\uff09=\uff0dcot\u03b1
tan\uff08\u03c0/2\uff0d\u03b1\uff09=cot\u03b1
cot\uff08\u03c0/2+\u03b1\uff09=\uff0dtan\u03b1
cot\uff08\u03c0/2\uff0d\u03b1\uff09=tan\u03b1
\u63a8\u7b97\u516c\u5f0f\uff1a
3\u03c0/2 \u00b1 \u03b1\u4e0e\u03b1\u7684\u4e09\u89d2\u51fd\u6570\u503c\u4e4b\u95f4\u7684\u5173\u7cfb\uff1a
sin\uff083\u03c0/2+\u03b1\uff09=\uff0dcos\u03b1
sin\uff083\u03c0/2\uff0d\u03b1\uff09=\uff0dcos\u03b1
cos\uff083\u03c0/2+\u03b1\uff09=sin\u03b1
cos\uff083\u03c0/2\uff0d\u03b1\uff09=\uff0dsin\u03b1
tan\uff083\u03c0/2+\u03b1\uff09=\uff0dcot\u03b1
tan\uff083\u03c0/2\uff0d\u03b1\uff09=cot\u03b1
cot\uff083\u03c0/2+\u03b1\uff09=\uff0dtan\u03b1
cot\uff083\u03c0/2\uff0d\u03b1\uff09=tan\u03b1
\u53c2\u8003\u8d44\u6599\uff1a\u4e09\u89d2\u51fd\u6570\u8bf1\u5bfc\u516c\u5f0f\u767e\u5ea6\u767e\u79d1
\u4e09\u89d2\u51fd\u6570\u4ee3\u6362\uff1a
cos2X=(cosX)^2-(sinX)^2=2*(cosX)^2-1=1-2*(sinX)^2
\u5373\uff1acos2x=2cosx\u7684\u5e73\u65b9-1=cosx\u7684\u5e73\u65b9-sinx\u5e73\u65b9=1-2sinx\u7684\u5e73\u65b9
\u5012\u6570\u5173\u7cfb\uff1a
\u2460 \uff1b
\u2461 \uff1b
\u2462
\u5546\u6570\u5173\u7cfb\uff1a
\u2460 \uff1b
\u2461 \uff0e
\u5e73\u65b9\u5173\u7cfb\uff1a
\u2460 \uff1b
\u2461 \uff1b
\u2462
\u6269\u5c55\u8d44\u6599\uff1a
\u8bf1\u5bfc\u516c\u5f0f\u53e3\u8bc0\u201c\u5947\u53d8\u5076\u4e0d\u53d8\uff0c\u7b26\u53f7\u770b\u8c61\u9650\u201d\u610f\u4e49\uff1a
k\u00d7\u03c0/2\u00b1a(k\u2208z)\u7684\u4e09\u89d2\u51fd\u6570\u503c\u3002
(1)\u5f53k\u4e3a\u5076\u6570\u65f6\uff0c\u7b49\u4e8e\u03b1\u7684\u540c\u540d\u4e09\u89d2\u51fd\u6570\u503c\uff0c\u524d\u9762\u52a0\u4e0a\u4e00\u4e2a\u628a\u03b1\u770b\u4f5c\u9510\u89d2\u65f6\u539f\u4e09\u89d2\u51fd\u6570\u503c\u7684\u7b26\u53f7\uff1b
(2)\u5f53k\u4e3a\u5947\u6570\u65f6\uff0c\u7b49\u4e8e\u03b1\u7684\u5f02\u540d\u4e09\u89d2\u51fd\u6570\u503c\uff0c\u524d\u9762\u52a0\u4e0a\u4e00\u4e2a\u628a\u03b1\u770b\u4f5c\u9510\u89d2\u65f6\u539f\u4e09\u89d2\u51fd\u6570\u503c\u7684\u7b26\u53f7\u3002
\u8bf1\u5bfc\u516c\u5f0f\u7684\u5e94\u7528\uff1a
\u8fd0\u7528\u8bf1\u5bfc\u516c\u5f0f\u8f6c\u5316\u4e09\u89d2\u51fd\u6570\u7684\u4e00\u822c\u6b65\u9aa4\uff1a
\u7279\u522b\u63d0\u9192\uff1a\u4e09\u89d2\u51fd\u6570\u5316\u7b80\u4e0e\u6c42\u503c\u65f6\u9700\u8981\u7684\u77e5\u8bc6\u50a8\u5907\uff1a
\u2460\u719f\u8bb0\u7279\u6b8a\u89d2\u7684\u4e09\u89d2\u51fd\u6570\u503c\uff1b
\u2461\u6ce8\u610f\u8bf1\u5bfc\u516c\u5f0f\u7684\u7075\u6d3b\u8fd0\u7528\uff1b
\u2462\u4e09\u89d2\u51fd\u6570\u5316\u7b80\u7684\u8981\u6c42\u662f\u9879\u6570\u8981\u6700\u5c11\uff0c\u6b21\u6570\u8981\u6700\u4f4e\uff0c\u51fd\u6570\u540d\u6700\u5c11\uff0c\u5206\u6bcd\u80fd\u6700\u7b80\uff0c\u6613\u6c42\u503c\u6700\u597d\u3002
\u53c2\u8003\u8d44\u6599\uff1a\u767e\u5ea6\u767e\u79d1\u2014\u2014\u4e09\u89d2\u51fd\u6570\u516c\u5f0f
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祝学习进步
cos2X
=(cosX)^2-(sinX)^2
=2*(cosX)^2-1
=1-2*(sinX)^2
如果您满意，请采纳答案！不懂可追问，谢谢！
倍角公式：
cos2x
=cos²x-sin²x
=2cos²x-1
=1-2sin²x
绛旓細cos2x=cos²x-sin²x =2cos²x-1 =1-2sin²x =(1-tan²x)/(1+tan²x)鍚岃涓夎鍑芥暟鐨勫熀鏈叧绯诲紡 鍊掓暟鍏崇郴锛歵an伪 路cot伪=1銆乻in伪 路csc伪=1銆乧os伪 路sec伪=1锛涘晢鐨勫叧绯伙細 sin伪/cos伪=tan伪=sec伪/csc伪銆乧os伪/sin伪=cot伪=csc伪/sec伪锛...
绛旓細cos2x绛変簬鍟ワ細cos2X=(cosX)^2-(sinX)^2 cos2x鏄笁瑙掑嚱鏁颁腑鐨勪綑寮﹀嚱鏁扮殑骞虫柟锛屽嵆(cosx)^2銆備笅闈㈡槸瀵筩os2x鐨勭畻娉曞拰瑙ｆ瀽鐨勮В閲婏細绠楁硶锛1銆佷娇鐢ㄤ笁瑙掑嚱鏁扮殑鍊嶈鍏紡锛歝os2x=cos^2x-sin^2x銆2銆佸皢cos^2x鍜宻in^2x琛ㄧず涓1-sin^2x锛屽嵆cos2x=1-2sin^2x銆傝В鏋愶細1銆乧os2x鍙互閫氳繃灏唜鐨勮搴﹀姞鍊嶆潵...
绛旓細cos2x绛変簬(1-tan²x)/(1+tan²x) 銆俢os2x=cos²x-sin²x =2cos²x-1 =1-2sin²x =(1-tan²x)/(1+tan²x)k脳蟺锛2卤a(k鈭坺)鐨勪笁瑙掑嚱鏁板 褰搆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...
绛旓細鍗砪os2x=2(cosx)^2-1=1-2(sinx)^2銆
绛旓細cos2x绛変簬1-2*(sinX)^2锛宻in2x绛変簬2sinx*cosx锛宑os2x灞炰簬涓夎鍑芥暟涓殑浜屽嶈銆傛帹瀵艰繃绋嬶細cos2X =(cosX)^2-(sinX)^2 =2*(cosX)^2-1 =1-2*(sinX)^2 鍊嶈鍏紡鎷撳睍锛氱敱鍊嶈鍏紡cos2x=2cos2x-1锛屽彲鐭os2x鍙互琛ㄧず涓篶osx鐨勪簩娆″椤瑰紡銆傚浜巆os3x锛屾垜浠湁 cos3x=cos锛2x+x锛=cos2xcosx...
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 cos2x鐨勫嚱鏁板浘鍍:
绛旓細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 褰搆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...
绛旓細cos2x绛変簬1-2sinx鐨勫钩鏂广俢os2x=cos²x-sin²x=2cos²x-1=1-2sin²x=锛1-tan²x锛/锛1+tan²x锛夛紝鍗筹細cos2x=2cosx鐨勫钩鏂-1=cosx鐨勫钩鏂-sinx骞虫柟=1-2sinx鐨勫钩鏂广俢os涔熷氨鏄綑寮︼紙浣欏鸡鍑芥暟锛夛紝涓夎鍑芥暟涓殑涓绉嶃備笁瑙掑嚱鏁版槸鍩烘湰鍒濈瓑鍑芥暟涔嬩竴锛屾槸浠ヨ搴︼紙...
绛旓細cos2x涓巘anx閮藉睘浜庝笁瑙掑嚱鏁扮殑璇卞鍏紡锛屼簩鑰呯殑鍏崇郴濡備笅锛1銆乻in²x+cos²x=1锛2銆乼anx=sinx/cosx锛3銆乧os2x=(1-tan²x)/(1+tan²x)锛4銆乧os2x=1-tan²x/tan²x+1銆備笁瑙掑嚱鏁拌瀵煎叕寮忕殑浣滅敤涓哄彲浠ュ皢浠绘剰瑙掔殑涓夎鍑芥暟杞寲涓洪攼瑙掍笁瑙掑嚱鏁般
绛旓細cos2x=cos²x-sin²x=2cos²x-1;濡傛灉鏈鏈浠涔涓嶆槑鐧藉彲浠ヨ拷闂紝濡傛灉婊℃剰璁板緱閲囩撼 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
