FTCE General Knowledge Math Practice Test 2025 – 400 Free Practice Questions to Pass the Exam

Two angles that add up to 180 degrees are called supplementary angles. This term is derived from the fact that when two angles combine to form a straight line, their measures are said to supplement one another. Supplementary angles can be either adjacent, sharing a common ray, or non-adjacent.

Complementary angles, on the other hand, are those that sum to 90 degrees. Adjacent angles refer to angles that are next to one another, sharing a common arm but not specifically defined by their sum. Obtuse angles are those that measure more than 90 degrees but less than 180 degrees; they do not have a specific relationship based on their sum with other angles. Therefore, the choice identifying the correct answer captures the essential definition tied to the sum of 180 degrees.