Octagon is an eight-sided two-dimensional geometric figure. Contains 8 interior and 8 exterior angles. Sum of interior angles is 1080°. Sum of exterior angles is 360°
Heptagon is a seven-sided polygon with seven angles, vertices, and edges. Also known as septagon or 7-gon. Contains fourteen diagonals
Polygon is a 2D shape made of straight lines with finite number of sides. Polygon comes from Greek 'poly' (many) and '-gon' (angle). All polygons have straight sides and corners called vertices. Circles are not polygons
Pentagon is a five-sided polygon with five angles. Sum of interior angles in regular pentagon is 540°. Regular pentagon has equal sides and angles. Each interior angle measures 108°, exterior angle 72°
Interior angle is formed inside a shape's two adjacent sides. Polygons can be regular (all angles equal) or irregular. Sum of interior angles equals 180°(n-2) for polygons of n sides
An octagon is a closed 2D shape with 8 sides and 8 angles. The sum of interior angles equals 1080°. There are 20 diagonals total