two angles are called complementary angles if they add up to 90 degrees, right? then what about 110 and -20? are they complementary? or complementary angles have to be both positive?
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When dealing with complementary angles, it's actually their magnitudes (sizes) that have to add to $\displaystyle 90^\circ$.
Originally Posted by Prove It When dealing with complementary angles, it's actually their magnitudes (sizes) that have to add to $\displaystyle 90^\circ$. so does that mean 30 and -60 are complementary?
Yes. If you were to draw both on the unit circle, you would have a $\displaystyle 90^{\circ}$ angle.
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