cos 2x = sin x dalam interval 0°

cos 2x = sin x
sin (phi/2 - 2x) = sin x

x = phi/2 - 2x + k.2phi
3x = phi/2 + k.2phi
x = phi/6 + k.2phi/3

k = 0, x = phi/6
k = 1, x = 5phi/6
k = 2, x = 3phi/2

x = -phi/2 + 2x + k.2phi
x = phi/2 - k.2phi
k = 0, x = phi/2

Hp = {phi/6 ;5phi/6 ;3phi/2 ;phi/2}