\(\cos(2x) = (\cos(x) + \sin(x)) \cdot (\cos(x) - \sin(x))\)

\(\sin(2x) = (\cos(x) + \sin(x)) \cdot (\cos(x) - \sin(x))\)

\(\cos(2x)= 2 \cos(x)\)

\(\sin(2x) = 2 \sin(x)\)