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tAn^2x=sEC^2x%1 Ϊʲô

⣺ (tanx)² =(sinx)²/(cosx)² =[1-(cosx)²]/(cosx)² =1/(cosx)²-1 =(secx)²-1

Ǻʽ֤

֤£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...

дԿDz 4tan^2x )*9cot^2x*12=4sec^2x* 9csc^2x-1 Ŀ壬Խ ѹʽдԼת sincsc=1 cossec=1 tan^2()+1=sec^2() cot^2()+1=csc^2()

tanx+½tan²x+CҲȷġ ֣òͬķʽпܻвͬڻֳϡ tanx+½tan²x+CͨΣõtanx+½sec²x+CҲȷ𰸡 tanx+½tan²x+C =ta...

=1/cos2x+sin2x/cosx =sec2x+tan2x=ұ ֤

(secx)'=(1/cosx)'=-1/cos^2 x *(cosx)'=sinx/cos^2 x=tanxsecx

f(x) = 1 g(x) = (secx)^2 - (tanx)^2 һ, ͬ ǰ x (-, +) , x k+/2, k Ϊ

Ǻʽ tan^2x+1=sec^2x

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