Toán Lớp 9: CMR
$\frac{1-sinx}{cosx}$ =$\frac{cosx}{1+sinx}$
mn giúp vs ạ
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Toán Lớp 9: CMR
$\frac{1-sinx}{cosx}$ =$\frac{cosx}{1+sinx}$
mn giúp vs ạ
Comments ( 1 )
Ta có :
sin²x + cos²x = 1
(=) cos²x = 1 – sin²x
(=) cosx² = (1 + sinx)(1 – sinx)
=> (1 – sinx)/cosx = cosx/(1 + sinx) (đpcm)