nilai x yang memenuhi cos (x+30°) = sin2x adalah...

semoga membantu jadikan jawaban terbaik

Cos (x + 30°) = sin 2x
Cos (x + 30°) = cos (90° - 2x)
x + 30° = 90° - 2x + k . 360°
x + 2x = 90° - 30° + k . 360°
3x = 60° + k . 360°
x = 20° + k . 120°
Jika k = 0 => x = 20°
Jika k = 1 => x = 140°
D