Y=3cos(x-30) cari nilai maksimum Dan minimum dengan cara

nilai maksimum

3×(1) = 3
3 = 3cos 0
cos 0 = cos (x-30)
x = 30°

minimum
3×(0) = 0
0 = 3 cos 90°
cos 90° = cos(x-30)°
x = 120°