[TEX]4sin^3x+4sin^2x+6cosx=0[/TEX]
[TEX]4sin^2x(sinx+1)+6cos2(\frac{x}{2})=0[/TEX]
[TEX]4sin^2x[cos(\frac{x}{2})+sin(\frac{x}{2})]^2+6cos2(\frac{x}{2})=0[/TEX]
[TEX]4sin^2x[cos(\frac{x}{2})+sin(\frac{x}{2})]^2+6[cos(\frac{x}{2})-sin(\frac{x}{2})][cos(\frac{x}{2})+sin(\frac{x}{2})]=0[/TEX]
[TEX][cos(\frac{x}{2})+sin(\frac{x}{2})](4sin^2x[cos(\frac{x}{2})+sin(\frac{x}{2})]+6[cos(\frac{x}{2})-sin(\frac{x}{2})])=0[/TEX]
[TEX]cos(\frac{x}{2})+sin(\frac{x}{2})=0[/TEX]
[TEX]4sin^2x[cos(\frac{x}{2})+sin(\frac{x}{2})]+6[cos(\frac{x}{2})-sin(\frac{x}{2})]=0[/TEX]