40 PCT.

7. Calculaţi:
a)
[tex] \sin ( - \frac{\pi}{4}) \: \: \: \cos( - \frac{\pi}{4} ) [/tex]


b)
[tex] \sin( - \frac{\pi}{3} ) \: \: \: \cos( - \frac{\pi}{3} ) [/tex]

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