Reference Angles

Question

Find the reference angle  , and sketch      in standard position.

Given  

Answer 1

Reference angles are between 0 and 90 degrees so I always change negative angles to positive coterminal angles by adding 360 to the negative angle. -135 + 360 = 225.

225 degrees is in the 3rd quadrant. To find the reference angle for the third quadrant. subtract 180 from the given angle.

225 - 180 = 45 degrees.