Question 426364
If you cannot determine the reference angle for some angle, then you must take advantage of the fact that all angles that are co-terminal will have the same reference angle. And co-terminal angles are multiples of 360 degrees apart from each other.<br>
So you can add (or subtract) multiples of 360 to change the original angle into a co-terminal one whose reference angle is easier to find. It is probably easiest to find reference angles for angles between 0 and 360 degrees. So you probably want to add (or subtract) 360's until you get a number between 0 and 360.<br>
With your negative angle we will want to add 360's:
-275 + 360 = 85
And already we have a co-terminal angle between 0 and 360. And since angles between 0 and 90 are their own reference angles, the reference angle for 85 (and -275) is 85.