
Rich G. answered 04/15/20
Experienced Pre-Calculus/Trigonometry Tutor
If you take the inverse sin of both sides of the equation then it becomes
x + 30° = sin-1 (1/2)
The inverse sin of 1/2 = 30° or 150°. Since we're told to look in quadrant II (90° < x 180°), we know that it must be 150°. Now are equation is
x + 30° = 150°
And you can solve for x from there.