The minimum positive period of function y = 1 / 2Sin & sup2; 3x No,

The minimum positive period of function y = 1 / 2Sin & sup2; 3x No,

I don't understand~
What does the symbol mean?
Is it sin ^ 2 (3x)
Then sin ^ 2 (3x) = {1-cos (6x)} / 2
The minimum positive period is t = 2pi / 6 = pi / 3