Question 69491
sin^2(0.5x) = 0.5(1 - cos(x))
sin^2(0.5x) = 0.5(1 - 1/9)
sin^2(0.5x) = 0.5(8/9)
sin^2(0.5x) = 4/9
sin(0.5x) = +- 2/3