It's d. You have to know here that measuring an angle usually happens going in the counterclockwise direction. If an angle is given as a positive measure then it has been measured from the positive x-axis and the terminal side has moved counterclockwise. Your angle is a -210. Therefore, it starts at the positive x-axis but moves clockwise. The first axis it passes, the negative y axis, the 90 degrees, the next axis it passes, the negative x axis, is 180 degrees. We need 30 more degrees to get from 1180 to 210, which puts us in QII with a 30 degree angle as the reference angle. The Pythagorean triple for a 30-60-90 degree special right triangle is, in terms of number values, [tex](1, \sqrt{3}, 2) [/tex] with the 1 being across from the 30 degree angle. So if the 1 is across from the 30 degree reference angle, that is parallel to the y axis, and the vertex angle is the 60 degree angle, and across from that angle is the side that measures square root of 3 which is along the x-axis. But in QII, x is negative. Therefore, your coordinates for a point on the terminal ray of a -210 degree angle is [tex](- \sqrt{3},1) [/tex]
