Jawab dgn caranya....!!

22][
f(x) = 2 sin (x/3)
f(90°) = 2 sin (90°/3)
f(90°) = 2 sin 30° = 2 . 1/2 = 1 ✔

23][
cos 3x = -1/2 √3
3x = 120° atau 3x = 240°
x = 40° atau x = 80°

24][
sin² x - 3 cos² x = 0
sin² x = 3 cos² x
(sin x / cos x)² = 3
tan² x = 3
tan x = ± √3
x = 60° atau x = 120°