More Lessons for Grade 11

Math Worksheets

Videos, worksheets, games and activities to help Algebra 2 students learn about reference angles.

Sine and cosine at non-acute angles

To find the value of sine and cosine at non-acute angles (from 90 to 360), first draw the angle on the unit circle and find the reference angle. A reference angle is formed by the terminal side and the x-axis and will therefore always be acute. When evaluating cosine and sine for the reference angle, determine if each value is positive or negative by identifying the quadrant the terminal side is in.

This video provides examples of how to determine the reference angle for an angle sketched in standard position.

Finding the reference angle given an angle

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You can use the free Mathway calculator and problem solver below to practice Algebra or other math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.