Question

Определить множество значений E(f) функции f(x)=cos3x , заданной на отрезке [pi/12;5pi/12]

Answer 1

cos(3*pi/12) = cos(pi/4) = √2/2;
cos(3*5pi/12) = cos(5*pi/4) = -√2/2;
E(f)=[-√2/2; √2/2]