Question

Persamaan trigonometri
cos 2x=-1/2
tolong pakai penyelesaian.

Answer 1

2x = arc cos 1/2= 60
x=60/2=30

Answer 2

2x = arccos(-1/2)
x = ?

cos2x = cos^2x - sin^x
cos2x = 1 - 2sin^x

1 - 2sin^2(x) = -1/2
2sin^2(x)= 3/2
sin^2(x) = 3/4
sin(x) = ± (√(3))/2
x = ± 60°