$$-2 \cos (x- \frac { \pi } { 2 } )+4 \cos ( \frac { \pi +x } { 2 } )$$
$2\left(-2\sin(\frac{x}{2})-\sin(x)\right)$
$$2\left(-\cos(\frac{2x-\pi }{2})+2\cos(\frac{\pi +x}{2})\right)$$
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