What is the nature of the angles in a triangle?

In any triangle, the sum of the interior angles is always 180 degrees. This fundamental property of triangles is a cornerstone of Euclidean geometry and applies to all types of triangles, regardless of their classification as scalene, isosceles, or equilateral.

This can be understood through various methods, such as drawing parallel lines and using alternate interior angles or by dividing a triangle into smaller triangles to show that the angles always add up to 180 degrees.

Recognizing that the sum is constant at 180 degrees helps in solving many problems related to triangles, such as angle calculations and establishing triangle congruencies. This rule is fundamental and remains true in any triangle drawn in a flat geometric plane.