bagaimana Cara Nomor 4 . beserta caranya . Tolong bantu saya . ini penting

2 cos 2(x - 75) = √3
cos 2(x - 75) = √3/2
2(x - 75) = 30
x - 75 = 30/2
x = 15 + 75
x = 90
2(x - 75) = -30
x - 75 = -30/2
x = -15 + 75
x = 60