(sinπ/7*cosπ/7*cos2π/7*cos3π/7)/(sinπ/7)=
=(sin2π/7*cos2π/7*cos3π/7)/(2sinπ/7)=(sin4π/7*cos3π/7)/(4sinπ/7)=
=(sin(π-3π/7)*cos3π/7)/(4sinπ/7)=(sin3π/7*cos3π/7)/4sinπ/7)=
=(sin6π/7)/(8sinπ/7)=sin(π-π/7)/(8sinπ/7)=(sinπ/7)/(8sinπ/7)=1/8
Держи формулу и по ней вычесли : S=V.t
-2 4/5 - 1 2/5 + 3 + 2/3= -4 1/5 + 3 + 2/3= -7.2 + 2/3
1 6\10 - 1\4 = 16\10 - 1\4 = 27\20
- 1 1\9 * 27\20 = -10\9 * 27\20 = - 3\2
-3\2 + 25\10 = 10\10 = 1
ответ : 1