T
tran_sigma@rocketmail.com


Câu 1 : [tex] tan^3x + tan^2x + tanx + 1 = \frac{Sinx + Cosx}{cos^3x}[/tex]
Câu 2 : [tex] \frac{Cos^2x - Sin^2x}{Sin^4x + Cos^4x - sin^2x} = 1 + Tan^2x [/tex]
Thanks các bạn....@};-
Câu 2 : [tex] \frac{Cos^2x - Sin^2x}{Sin^4x + Cos^4x - sin^2x} = 1 + Tan^2x [/tex]
Thanks các bạn....@};-