What is the sum of the angles in a triangle?

In a triangle, the sum of the interior angles is always 180 degrees. This fundamental property holds true for all types of triangles—whether they are scalene, isosceles, or equilateral. The reasoning behind this can be understood through various geometrical proofs, including the parallel line postulate, where a triangle can be inscribed between two parallel lines, demonstrating that the angles formed on a transversal add up to 180 degrees.

When you consider the possibilities provided, options such as 360, 90, and 270 degrees do not align with the established properties of triangle geometry. A circle, for example, contains 360 degrees, which corresponds to the total sum of angles around a point, not within a triangle. Similarly, 90 degrees represents the sum of angles in a right triangle when combined with one other angle, and 270 degrees would suggest a different geometric context altogether, which does not pertain to the angles in a triangle. Thus, the only valid sum for the angles in any triangle remains at 180 degrees.