又有數唔識啊，關於Trigonometry

cos (150+θ) = sin 120

cos(90 + 60 + θ) = sin120

-sin(60 + θ) = sin120

60 + θ = 240 or 300

θ = 180

sin(2θ - 60) = 1/2 = sin30 or sin 150

2θ - 60 = 30 or 150

θ = 45 or 105

sinθ = cos110 = cos(90 + 20) = -sin20

θ = 200 or 340

cos(150 + θ) = sin120 = sin(180 - 120) = sin(60) = cos(90 - 60) = cos(30)
0 <= θ <= 180 -> 150 <= 150 + θ <= 330
150 + θ = 330 since 0 <= θ <= 180
θ = 180

0 <= θ <= 180
sin(2θ - 60) = 1/2 = sin(30)
0 <= θ <= 180 -> -60 <= 2θ - 60 <= 300
2θ - 60 = 30 or 150 since 0 <= θ <= 180
i.e. θ = 45 or 105

sinθ = cos110 = sin(90 - 110) = sin(-20)
θ = 180 - (-20) or θ = 360 + (-20) for 0 <= θ <= 360
θ = 200 or 340