y = 1-cosx
cosx: [-1; 1], E(y): [0; 2]
y = 1 - 4cos2x
cos2x: [-1; 1], E(y): [-3; 5]
y = (1/2) sinx*cosx - 1 = (sin2x)/4 -1
sin2x: [-1; 1], E(y): [(-5/4); (-3/4)]
y = 1-cosx
cosx: [-1; 1], E(y): [0; 2]
y = 1 - 4cos2x
cos2x: [-1; 1], E(y): [-3; 5]
y = (1/2) sinx*cosx - 1 = (sin2x)/4 -1
sin2x: [-1; 1], E(y): [(-5/4); (-3/4)]