How to Work Out Interior and Exterior Angles: Understanding the Calculation of Angles in ShapesSarah ThompsonJan 14, 2026Table of ContentsQuick SummaryCalculating Interior AnglesCalculating Exterior AnglesPractical Applications of Angle CalculationsFAQFree Smart Home PlannerAI-Powered smart home design software 2025Home Design for FreeQuick Summary- The sum of a polygon’s interior angles is (n − 2) × 180°, e.g., triangle 180° and square 360°.- The sum of all exterior angles of any polygon is always 360°.- In a regular pentagon, each exterior angle measures 360° ÷ 5 = 72°.Calculating interior and exterior angles is essential in geometry, especially in understanding shapes and their properties. Interior angles are the angles inside a shape, while exterior angles are formed outside of a shape when a side is extended. To find these angles, you can use specific formulas and the properties of polygons.Calculating Interior AnglesTo determine the sum of the interior angles of a polygon, you can use the formula: (n - 2) × 180°, where n is the number of sides in the polygon. For instance, a triangle has three sides, so its interior angles sum up to (3 - 2) × 180° = 180°. For a square, which has four sides, the sum is (4 - 2) × 180° = 360°.Calculating Exterior AnglesThe sum of all exterior angles of any polygon is always 360°, regardless of the number of sides. To find the measure of each exterior angle, you can divide the total sum by the number of sides. For example, in a regular pentagon (5 sides), each exterior angle measures 360° ÷ 5 = 72°.Practical Applications of Angle CalculationsUnderstanding how to work out interior and exterior angles is crucial not just in mathematics but also in fields like architecture and interior design. For instance, when designing a room, knowing these angles can help ensure that furniture fits well and aesthetics are maintained. If you're ever looking to visualize your designs, consider using tools like room planners for better accuracy.FAQWhat is the formula for finding the interior angles of a polygon? Use (n - 2) × 180°. What is the sum of the exterior angles of a polygon? Always 360°.welcome to CoohomHome Design for FreePlease check with customer service before testing new feature.