Himpunan penyelesaian dari persamaan 2.cos 4x - 1 = untuk 0° < x < 360° adalah..

2.cos 4x = 1
cos 4x = ½
4x = 60
x = 60/4 = 15
4x = 300
x = 300/4 = 75
4x = 420
x = 420/4 = 105
4x = 660
x = 660/4 = 165
4x = 780
x = 780/4 = 195
4x = 1020
x = 1020/4 = 255
4x = 1140
x = 1140/4 = 285
4x = 1380
x = 1380/4 = 345
hp {15,75,105,165,195,255,285,345}