[m]=lim_{x → 0}\frac{sin9x}{9x}\cdot \frac{3x}{arctg3x}\cdot\frac {9x}{3x}=3[/m]
2)
1-cos^22x=sin^22x
[m]=lim_{x → 0}\frac{sin^22x}{sin^24x}=lim_{x → 0}\frac{sin2x\cdot sin2x}{sin4x\cdot sin4x}=[/m]
[m]=lim_{x → 0}\frac{sin2x}{2x}\cdot \frac{sin2x}{2x}\cdot \frac{4x}{sin4x}\cdot \frac{4x}{sin4x}\cdot \frac{2x\cdot 2x}{4x\cdot 4x}=\frac{1}{4}[/m]