Complementary angles add up to ninety degrees. Triangles must hold 180.
Taking these facts together, think of this: you have two angles in a triangle where they add up to ninety. This means that the other angle in the triangle must hold the other ninety.
I'm not going to answer your question, but I'll pose you the question you should have asked: What is a triangle called when it has one angle that is exactly ninety degrees?
Chat with our AI personalities
The two angles, other than the right angle itself, MUST be complementary.
The sum of two complementary angles is 90 degrees. The three angles of a triangle add up to 180 degrees. Hence, if you subtract the complementary angles from 180, you have the measure of the third angle: 180 - 90 = 90 (this is the third angle) As a rule, if two angles of a triangle are complementary, the third angle is a right angle (90 deg). The three angles together form a right triangle.
The complementary angles form a right angle with the shared ray.
Complimentary angles
No, one of two complementary angles cannot be obtuse, because only two acute angles that add up to 90 degrees are complementary and that an obtuse angle on its own is greater than 90 degrees.