\(=\dfrac{2sin2x.cos^22x}{\left(1+2cos^22x-1\right)\left(1+2cos^2x-1\right)}=\dfrac{4sinx.cosx.cos^22x}{4cos^22x.cos^2x}\)
\(=\dfrac{sinx}{cosx}=tanx\)
Rút gọn 
rút gọn: \(\dfrac{1-2sin^2x}{cos2x-sin2x}\)
Rút gọn: \(\dfrac{sina+cosa-1}{sina-cosa+1}\)
Rút gọn biểu thức: 3(sin8x - cos8x) + 4(cos6x - 2sin6x) + 6sin4x
rút gọn
\(\dfrac{sin2a+1}{cos2a}-\dfrac{1-sin2a}{sina-cosb}\)
Rút gọn biểu thức A= (1+cotx)sin^3x+(1+tanx)cos^3x
Rút gọn :\(\dfrac{cos2\alpha+cos4\alpha+cos6\alpha}{sin2\alpha+sin4\alpha+sin6\alpha}\)
rút gọn
\(\dfrac{\sin^2x-\cos^2x+\cos^4x}{\cos^2x-\sin^2x+\sin^4x}\)
A=cos(a-pi/3)-sin(a-pi/6), rút gọn A s ạ
