Question 310722
We need to find values for theta (in degrees) that lie between 0 and 180 degrees.  We are looking at the first and second quadrants only.

Let t = theta in the equation since I do not have a theta key on the keyboard.

2sin(t) - 1 = 0

Adding 1 to both sides we get:

2sin(t) = 1

Now divide both sides by 2.

sin(t) = 1/2

From the unit circle (that you should memorize), we learn that the values of theta when sine = 1/2 are:  30 degrees and 150 degrees.

NOTE: 30 degrees lies in quadrant 1 and 150 degrees lies in quadrant 2.