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

The sum of the interior angles of a triangle is always 180 degrees. This fundamental property arises from the geometric definition of a triangle, which consists of three sides and three angles. When you take a straight line and draw two rays from one endpoint, the angle formed by these rays remains constant, and if you were to sum the angles within the triangle formed by these rays and a third line, it would precisely equal 180 degrees.

This relationship holds true for all types of triangles, whether they are equilateral, isosceles, or scalene. Therefore, understanding that the interior angles always sum to 180 degrees is crucial for solving various geometric problems involving triangles.

The other choices do not reflect the fundamental theorem concerning triangles. For example, a sum of 90 degrees pertains to the angles of a right triangle if you consider one angle as 90 degrees, but not the total for all angles. A sum of 270 degrees or 360 degrees corresponds to polygons with more sides or specific configurations but does not apply to triangles. Hence, recognizing that the interior angles of any triangle total 180 degrees is essential for mastering geometric concepts.