Answer:
√5/3.
Step-by-step explanation:
Using the identity sin^2 O + cos^ O = 1
sin^2 O = 1 - cos^2 O
sin^2 O = 1 - (2/3)^2
sin^2 O = 1 - 4/9
sin^2 O = 5/9
sin O = √(5/9)
sin O = √5/3.