This will have a max value where the sin = 1..this happens at pi/2.....this means that we need to find where [2x - pi/3] = pi/2
So......solving for x, we have that
2x - pi/3 = pi/2 add pi/3 to both sides
2x = [ 5pi/6] divide both sides by 2
x = 5pi / 12 .......and it will reach that max at every ± pi rads from this value
To find out where it has a min....we need to find out where the sin = -1...this happens at 3pi/2....thus, we need to find out where
2x - pi/3 = 3pi/2 add pi/3 to both sides
2x = 11pi/6 divide both sides by 2
x = 11pi/12 ........and it wil,. again, have a min at every ±pi rads from this value
See the graph, here : https://www.desmos.com/calculator/ohrm0oeuul