The answers are pi/3, 2pi/3.
Step-by-step explanation:
Because of our special triangles, we know cos(pi/6) is root 3 over 2. therefore we plug in root 3 over 2 instead of cos(pi/6)
sinx= root 3/2
Next, because of CAST, we know sin is positive in quadrants 1 and 2.
To find our reference angle, we use the special triangles again and see that our reference angle is pi/3.
The reference angle pi/3 in quadrant 1 is pi/3 and in quadrant two it is 2pi/3.
Those are your answers!