[tex] \sin(2x) = 2 \sin(x) \cos(x) \\ \\ \sin(2x) = \sin(x \times x) \\ \\ \sin(2x) = \sin(2x) [/tex]
adevărat
b)
[tex] \sin( \frac{\pi}{2} - x ) = \cos(x) \\ \\ \sin( \frac{\pi}{2} ) \cos(x) - \cos( \frac{\pi}{2} ) \sin(x) = \cos(x) \\ \\ 1 \cos(x) - 0 \sin(x) = \cos(x) \\ \\ \cos(x) - 0 = \cos(x) \\ \\ \cos(x) = \cos(x) [/tex]
adevărat
