Найду корень уравнения: cos(x)=7/5
True
x1 = 2*pi - I*im(acos(7/5))
x2 = I*im(acos(7/5)) + re(acos(7/5))
сумма
2*pi - I*im(acos(7/5)) + I*im(acos(7/5)) + re(acos(7/5))
=
2*pi + re(acos(7/5))
произведение
(2*pi - I*im(acos(7/5)))*(I*im(acos(7/5)) + re(acos(7/5)))
=
(2*pi - I*im(acos(7/5)))*(I*im(acos(7/5)) + re(acos(7/5)))