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ǰλãҳ >> sEC2x%tAn2x=1?Ϊʲô? >>

sEC2x%tAn2x=1?Ϊʲô?

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

ϸдֽ

֤£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...

=1/cos2x+sin2x/cosx =sec2x+tan2x=ұ ֤

tanx = sinx/cosx (tanx)^2 = (sinx)^2/(cosx)^2 =(1- (cosx)^2 )/(cosx)^2 = 1/(cosx)^2 -1 =(secx)^2 -1 Tanе˼ǦֱУӦĶԱڱߵıֵǦȵֵȷֱϵмtan=y/xtanA=Ա/...

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

=1/cos2xһsin2x/cos2x =(1һsin2x)/cos2x =(1һ2sinxcosx)/(con^xһsin^x) =(sinһconx)/(sinxʮcosX)

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)~~

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