reference angle of cosine of 510 degrees?

Catheryn Small: The reference angle is the positive acute angle that can represent an angle of any measure. Basically, any angle on the x-y plane has a reference angle, which is always between 0 and 90 degrees. The reference angle is always the smallest angle that you can make from the terminal side of an angle (ie where the angle ends) with the x-axis. A refrerence angle always uses the x-axis as its frame of rerence. Very understandable examples are in http://www.mathwarehouse.com/trigonometry/referenc... First simplify 510 by subtracting 360 continuously until you get a value less than 360. Here 510 is equal to 150 degrees. Now the smallest angle with reference to the x-axis should be near the 180 degrees mark. 180-150 which is 30 degrees....Show more