Пусть An=(-1)^n sin pi n/18. Тогда сумма a6+a24=
Вычисляем A6: A6 = ((-1)^6) * sin(π *6/18) = sin(π/3) = √3 /2 Вычисляем A24: A24 = ((-1)^24)* sin(π*24/18) = sin(4π/3) = sin(π + π/3) = -sin(π/3) = -√3 /2 Вычисляем A6 + A24: A6 + A24 = √3 /2 - √3 /2 = 0
A6=(-1)^6*sin(6π/18)=sinπ/3=√3/2 a24=(-1)^24*sin(24π/18)=sin4π/3)=sin(π+π/3)=-sinπ/3=-π3/2 a6+a24=√3/2-√3/2=0