👤
Lilliana15
a fost răspuns

Cos patrat de 15 - cos patrat de 75 = ?
Am mare nevoie de ajutoooor :( :)


Răspuns :

cos²15°-cos²75°=(1+cos2*15°)/2-(1+cos2*75°)/2=(1+√3/2)/2-(1+cos(180°-30°))/2=(2+√3)/4-√3/4=(2+√3-√3)/4=2/4=1/2