Angle x is a third quadrant angle such that cosx=−23 .
What is the exact value of cos(x2) ?
Enter your answer, in simplest radical form, in the box.
cos x = -2 / 3
cos (x/2) = - sqrt [ ( 1 + cos x) / 2 ] = -sqrt [ (1 - 2/3) / 2] =
-sqrt [ (1/3) / 2 ] =
- sqrt (1/6) =
- sqrt (6) / 6
