What is the sum of the angles in a triangle?

In the context of geometry, the sum of the interior angles of any triangle is always 180 degrees. This is a fundamental property of triangles that holds true regardless of the type or size of the triangle, whether it is scalene, isosceles, or equilateral.

This characteristic can be understood through the use of parallel lines and transversals in Euclidean geometry. By drawing a line parallel to one side of the triangle through the opposite vertex, the corresponding angles formed with the other two sides of the triangle can be demonstrated to sum to 180 degrees.

The other options represent common misconceptions or relate to different geometrical shapes. For instance, 90 degrees is the sum of the angles in a right triangle, but it does not apply universally to all triangles. Angles summing to 270 degrees or 360 degrees pertain more to polygons with more sides or specific configurations rather than the defining features of a triangle. Thus, the understanding that the sum must be 180 degrees is key in both foundational geometry and its applications.