[TEX]C= \frac{sin^2 2x - 4sin^2x}{sin^2 2x + 4 sin^2 x - 4} [/TEX]
[TEX]=\frac{1 - cos^2{2x} - 4.sin^2x}{1 - cos^2{2x} + 4.sin^2x - 4}[/TEX]
[TEX]=\frac{1 - (1 - 2.sin^2x)^2 - 4.sin^2x}{1 - (1 - 2.sin^2x)^2 + 4.sin^2x - 4}[/TEX]
[TEX]=\frac{4.sin^4x}{4.sin^4x - 8.sin^2x + 4}[/TEX]
[TEX]=\frac{sin^4x}{(sin^2x - 1)^2}[/TEX]