If cos x=-1/3 and x is in (90,180), calculate sin x=?

Because x is an angle located in the second quadrant, the value of the function sine is positive.

For finding the value of sine function, we'll use the fundamental formula of trigonometry:

(sin x)^2 + (cos x)^2 = 1

sin x = +sqrt[1-(cos x)^2]

sin x = +sqrt(1 - 1/9)

sin x = +sqrt(9-1)/9

sin x = +2sqrt2/3