Classification of angles: acute, right...complementary, supplementary...adjacent...
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Next, we'll look at the different ways angles are classified: according to the amplitude or opening of a single angle (acute, right, obtuse, convex, straight/collinear, concave, null, or complete/perigonal), according to the sum of several angles (complementary, supplementary, or conjugate), and according to whether two angles share a vertex and a side.