7-4 Finding a Reference Angle

Last week in class, the advance math students learned how to find reference angles. At first, the concept seemed difficult to grasp, but after days of practice the concept almost seemed similar to second nature.Here is a step by step list on how to solve

- To Find a Reference Angle

1.Find the Quadrant the angle is in


2.Determine if the trig function is positive or negative


3. Subtract 180 degrees from the angle until the absolute value is between 0 and 90 degrees.


4. If it is a trig chart angle ,plug in. If not, leave it or plug it in a calculator.


*Hint: Evaluate means number answer unless otherwise is specified.



Trig Chart: 0-0 degrees, 30 degrees- pi/6,45 degrees- pi/4, 60 degrees-pi/3, 90 degrees-pi/2




Ex: Find the Reference Angle for SIN 695 degrees.

1st step: Locate the quadrant. Since its 695 degrees, it'll be located in the 4th quadrant which is - +. 2nd step: you have to subtract 360 from 695 that will get you 335(which is the coterminal)

3rd step: you subtract 180 from 335 until u get -25.

Since 695 is in the 4th quadrant..sin 695<0 695 =" -sin25">