**Heptagon** is a type of polygon that is composed of 7 lines bounded together. It is a two-dimensional figure. Therefore, a heptagon has seven sides as well as seven angles. The angles are always found at the vertices. It is also called septagon, but heptagon is more popular name.

**Sum of Interior Angles:** The general formula for the sum of all interior angles of a polygon is given by –

(n−2)180^{0}

where, n = number of sides.

Therefore, the sum of interior angles of a heptagon will be

(7−2)180^{0}

= 5 x 180^{0}

= 900^{0}

**Sum of Exterior Angles**: Sum of exterior angles of a heptagon (like all polygons) is 360^{0}.

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**Types:**

**Regular Heptagon:** A regular heptagon is a heptagon that has congruent sides and angles.

**Irregular Heptagon:** An irregular heptagon is any heptagon with sides and angles that are not all congruent.

**Convex Heptagon:** A convex heptagon is a polygon with seven sides in which all of its diagonals lies inside the Heptagon.

**Concave Heptagon: **A Concave Heptagon is a polygon with one or more interior angles greater than 180 degrees and some diagonals will lie outside the polygon. Heptagons that are not convex are concave Heptagons.