- $ F\\\left( x \\\right) = 2\\\cos 2x$
- $ F\\\left( x \\\right) = \\\frac{1}{2}\\\cos 2x$.
- $ F\\\left( x \\\right) = {\\\sin ^2}x$.
- $ F\\\left( x \\\right) = - \\\cos 2x + 5$.