What does the term "complementary set" refer to in geometry?

The term "complementary set" in geometry specifically refers to angles that sum to 90 degrees. When two angles are complementary, their measures add up to a right angle. This concept is fundamental in understanding various geometric principles and is frequently applied in problems involving angle relationships in geometric figures.

For instance, if one angle measures 30 degrees, its complementary angle would measure 60 degrees because 30 + 60 = 90. Understanding complementary angles is crucial for solving problems in both planar geometry and trigonometry, as it relates to the behavior of angles formed by intersecting lines or within polygons.

The other options relate to different geometric concepts. The interior points of a set, the totality of points in a plane, and lines that do not intersect do not pertain specifically to the definition of complementary angles. Therefore, "angles that sum to 90 degrees" accurately defines complementary angles, making it the correct choice.