Berapa nilai x dari Cos3x = sin3x ; 0 kurang dari sama dengan x kurang dari sama dengan 2phi

cos 3x = sin 3x.
cos 3x = cos (90-3x)
3x = 90 -3x
6x = 90 + k.360
x = (90 + k.360)/6
x = 15 + k.60
k = 0, x = 15
k = 1, x = 75
k = 2, x = 135
k = 3, x = 195
k = 4, x = 225
k = 5, x = 285
k = 6, x = 345
k = 7, x = 405 (tidak dipakai karena di luar intefval)
HP = { 15,75,135,195,225,285,345 }

TriGonoMetRi

cos 3x = sin 3x
cos 3x = cos (90 - 3x)
3x = 90 - 3x + k.360°
6x = 90 + k.360
x = 15° + k.60°

Interval : 0 ≤ x ≤ 2π

NiLai x yg memenuhi :
k = 0 ---> x = 15° = 1/12 π
k = 1 ---> x = 75° = 5/12 π
k = 2 ---> x = 135° = 3/4 π
k = 3 ---> x = 195° = 13/12 π
k = 4 ---> x = 255° = 17/12 π
k = 5 ---> x = 315° = 7/4 π