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ǰλãҳ >> sEC2x%tAn2x=1?Ϊʲô? >>

sEC2x%tAn2x=1?Ϊʲô?

Ϊ sec²x-tan²x =1/cos²x-sin²x/cos²x =(1-sin²x)/cos²x =1

֤£tan²x=sin²x/cos²x=(1-cos²x)/cos²x=1/cos²x-1=sec²x-1 ֤Ĺʽ£ 1ƽϵ sin^2()+cos^2()=1 tan^2()+1=sec^2() cot^2()+1=csc^2() 2Ĺϵ sin=tan*c...

ϸдֽ

¥ԭʽ1+tan^2xɻΪ

=1/cos2x+sin2x/cosx =sec2x+tan2x=ұ ֤

sec²xtan²xĹϵ: tan²x=sec²x/sin²x tanxĵΪsec²x secxĵΪtanxsecx tan²x=sin²x/cos²x sec²x=1/cos²x sec²x-1= tan²x (1) ƽϵ:(sinx)^2+(cosx)^2=11+...

Ǻʽ tan^2x+1=sec^2x

sec^2x=1/cos^2x,sec^2x-1=(1/cos^2x)-1=(1-cos^2x)/cos^2x=sin^2x/cos^2x=tan^2x ʵؼǸ㶮secx=1/cos(x)~~

Ǻʽ֤

⣺ tan²x=sin²x/cos²x=(1-cos²x)/cos²x=1/cos²x-1=sec²x-1 Ϊsecx=1/cosx

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