Use the unit circle to find all values of thetabetween 0 and 2Ï€ for which sin (theta) = sqrt 3/2

Sin (theta) = √3/2, 0≤theta≤360

In a unit circle, sin is y/r, r is always positive, y is positive in the first and second quadrant only.

sin60=√3/2, sin120=√3/2

so theta is 60 or 120