Final answer:
The question asks for a fill-in-the-blank answer about angle relationships. If two angles add up to 90 degrees, they are complementary. If they add up to 180 degrees, they are supplementary. In the context of a triangle, the angles always add up to 180 degrees.
Step-by-step explanation:
If the sum of the measures of two angles is 90 degrees, then the angles are complementary. Complementary angles are two angles whose measures add up to 90 degrees. Examples of complementary angles are 30 degrees and 60 degrees, or 45 degrees and 45 degrees. Each pair totals 90 degrees when combined.
If the sum of the measures of two angles is 180 degrees, then the angles are supplementary. Supplementary angles are two angles whose measures have a sum of 180 degrees. Examples of supplementary angles include 130 degrees and 50 degrees, or two angles of 90 degrees each.
Regarding the properties of triangles, it's important to remember that according to geometry, if you are thinking of a triangle, you must think of a three-sided figure lying on a plane with three angles adding up to 180 degrees. This is a fundamental property of triangles in Euclidean geometry, which holds true irrespective of the type of triangle.