Răspuns:
[tex]x = ( \frac{\pi}{2} \times \pi) = \sin(x) >0 \\ \sin(x) = \sqrt{1 - { \cos}^{2}x} = \sqrt{1 - \frac{9}{16} } = \sqrt{ \frac{7}{16} } = \frac{ \sqrt{7} }{4} \\ \cos(x + \frac{\pi}{4}) = \cos(x)cos \frac{\pi}{4} - \sin(x)sin \frac{\pi}{4} [/tex]
rezolvarea e sus
sper sa te ajute
♧♧♧==irina334==♧♧♧
