When calcium hydroxide dissolves, it dissociates into
Ca(OH)2 = Ca2+ and 2OH-
Let's assign the variable X for the solubility of Ca2+ and OH
I.e Ca2+ = X and 2OH- = 2X
Then Ksp = [Ca2+][OH-]^2
So we have (X) (2X)^2 = 5.02 * 10^(-6)
4X^3 = 5.02 * 10 ^(-6)
X^3 = 5.02 * 10^(-6) / 4
X^3 = 0.003110
X = 0.1459