Nicaadriana97ask
a fost răspuns

calculati: s=cos0 grade+cos10 grade+cos20 grade+....+cos170 grade+cos180 grade

Răspuns :

Matepentrutotiask
[tex]cos0+cos180=2cos \frac{180+0}{2} cos \frac{180-0}{2} =2cos90cos90=0\\ cos10+cos170=2cos \frac{170+10}{2} cos \frac{170-10}{2} =2cos90cos80=0\\ ....\\ cos80+cos100=2cos \frac{100+80}{2} cos \frac{100-80}{2} =2cos90cos10=0\\ cos90=0\\ s=0[/tex]