1.himpunan penyelesaian persamaan 6cos x=-3 untuk 0

jawab

1)  6 cos x = 3
cos x = 3/6 = 1/2
cos x = 1/2 = cos π/3
x = π/3 +n. 2π   atau x = - π/3+ n. 2π
n = 0,1,2,3,4,...
n=0 , x =π/3 x = - π/3
xpada interval 0 < x < π
HP x = (π/3)

(2)
2 cos 3x = 1
cos 3x = 1/2 = cos 60
3x = 60 + n. 360  atau 3x = - 60 + n. 360
x = 20 +n.120  atau x = - 20 +n.120
n = 0, x = 20 , x = -20
n = 1, x = 140 , x = 100
n = 2. x = 260 , x = 220

untuk  0 < x < 180
x = (20, 100, 140)