Sum of angles in a triangle = 180°.

Wed, 06 May 2026 15:31:33 +0000

Understanding the Sum of Angles in a Triangle = 180°: The Fundamental Rule of Triangles When learning basic geometry, one of the most foundational and widely recognized facts is that the sum of the interior angles in any triangle equals 180 degrees. This principle is not just a mathematical curiosity—it's a cornerstone of Euclidean geometry and a key concept used across architecture, engineering, design, and even in everyday problem-solving. ### What Does It Mean for the Sum of Angles in a Triangle to Be 180°? A triangle is a three-sided polygon, and despite its simple appearance, its internal angles obey precise mathematical rules. In any triangle—whether equilateral, isosceles, scalene, or right-angled—the three angles placed inside the shape always add up to exactly 180 degrees.