1-cos²x-1cos 4x-1caranya gimananya?

[tex]1 - \cos{}^{2} x = sin {}^{2} x \\ cos \: 4x = 1 - 2sin {}^{2} \frac{1}{2} x \\ [/tex]
maka:
[tex]sin {}^{2} x -1 (1 - 2 \sin{}^{2} \frac{1}{2}x ) - 1 \\ = sin {}^{2} x - 1 + 2sin {}^{2} \frac{1}{2} x - 1 \\ = sin {}^{2} x + 2sin {}^{2} \frac{1}{2} x - 2[/tex]