Pembahasan:
sin(2x + 110°) + sin(2x – 10)° = ½
⇒ 2 sin½((2x + 110) + (2x – 10)) cos½((2x + 110) – (2x – 10)) = ½
⇒ 2 sin(2x + 50)° . cos 60° = ½
⇒ 2 sin(2x + 50)° . ½ = ½
⇒ sin(2x + 50)° = sin 30°
Penyelesaian 1:
2x + 50 = 30 ± k.360
x = –10 ± k.180
k = 1 ➔ x = 170
k = 2 ➔ x = 350
k = 3 ➔ x = 530 (tidak tergolong)
Penyelesaian 2:
2x + 50 = (180 – 90) ± k.360
2x + 50 = 150 ± k.360
x = 50 ± k.180
k = 0 ➔ x = 50
k = 1 ➔ x = 230
Himpunan penyelesaian: 50, 170, 230, 350