There are three acute angles:
There are three obtuse angles:
There are two right angles:
Two congruent angles
are vertical angles, so they are congruent.
Two straight angles
are straight.
Complementary angles
There is only one set of angles that combine to make 90°:
Supplementary angles
There are many sets of supplementary angles. Here are three of them:
are vertical angles, so they are congruent.
are straight. 
