Answer:
x = -5/6
Step-by-step explanation:
Since it is on the unit circle
x^2 + ( -sqrt(11)/6)^2 = 1 ^2 (pythagorean theorem)
x^2 = 1 - 11/36
x^2 = 25 /36
x = +-5/6 since x is in Q III it is the negative