How do you find the related acute angle?

1 Answer
Johnson Z.
Nov 26, 2015

The related acute is an acute angle (<90∘) that can be found between the terminal arm and the x-axis when the terminal arm is in quadrants 2, 3, or 4. There is no related acute angle if the terminal arm lies in quadrant 1.

Here are some examples:

![http://slideplayer.com/slide/4747145/](useruploads.socratic.org)

If the terminal arm is in quadrant 2, do 180∘ minus the principle angle to find the related acute angle.

If the terminal arm is in quadrant 3, do the principle angle minus 180∘ to find the related acute angle.

If the terminal arm is in quadrant 4, do 360∘ minus the principle angle to find the related acute angle.

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