Let be the measure of an angle, in radians, in standard position with /2 <

Let θ be the measure of an angle, in radians, in standard position with π/2 < θ < π. Find the exact x -coordinate of the intersection of the terminal side of θ with the unit circle, given cos²θ - sinθ = −1/9. State the answer as a single fraction, completely simplified, with rationalized denominator.