What is the sum of the interior angles of a triangle?

The sum of the interior angles of a triangle is 180 degrees. This fundamental property of triangles arises from the fact that when you draw a triangle, the three angles formed at each vertex are always complementary to one another, totaling 180 degrees. This can also be demonstrated through geometric principles such as the triangle's relationship to parallel lines, where drawing a line parallel to one side of the triangle can help visually confirm that the angles indeed add up to 180 degrees.

This concept is crucial in geometry as it lays the foundation for various other properties and theorems related to triangles and polygons in general. Understanding this helps in solving numerous problems in both theoretical and practical applications of mathematics.