What is the sum of the angles in a triangle?

The sum of the angles in a triangle is always 180 degrees, regardless of the type of triangle (whether it's equilateral, isosceles, or scalene). This fundamental property of triangles is a crucial concept in geometry. If you take any triangle and measure its interior angles, you will find that when you add them together, they total exactly 180 degrees.

This rule holds true for all triangles in Euclidean geometry. It can also be visualized by drawing a line parallel to one side of the triangle and noting how the angles relate to this configuration, reinforcing that the interior angles combine to form a straight line, which is 180 degrees.

Thus, the correct answer encapsulates this basic geometrical principle, making it essential knowledge in both algebra and geometry contexts.