Question

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

Answer 1

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