sin(2x+70°)=cos 40° tentukanlah nilai x

sin (2x + 70) = cos 40
sin (2x + 70) = sin (90 - 40)
sin (2x + 70) = sin 50

2x + 70 = 50 + n x 360
2x = 50 - 70 + n x 360
x = (- 20 + n x 360) / 2
x = - 10 + 180n

n = 0
x = -10 + 0 = -10

n = 1
x = -10 + 180 x 1 = 170

atau

2x + 70 = (180 - 50) + n x 360
2x = 130 - 70 + 360n
x = (60 + 360n)/2
x = 30 + 180n

n = 0
x = 30 + 180 x 0 = 30
HP = {30, 170, 0 ≤ x ≤ 180}