cosecant is one of the six trigonometric identities which is equal to the reciprocal of sine function. In this case, theta is equal to sin -1 = 1/2 equal to 30 degrees. Since this is in quadrant II, the angle is 180 - 30 or 150 degrees. cos 150 is equal to -0.866 or -ssqrt 3 over 2.
