What is a decagon?

A decagon is a polygon with ten sides and ten angles. Here's some information about them:

  • Types: Decagons can be regular (all sides and angles are equal) or irregular (sides and angles are of different lengths and measures).

  • Interior Angles: The sum of the interior angles of any decagon is (10-2) * 180° = 1440°. In a regular decagon, each interior angle measures 1440°/10 = 144°.

  • Exterior Angles: The sum of the exterior angles of any decagon (one at each vertex) is always 360°. In a regular decagon, each exterior angle measures 360°/10 = 36°.

  • Diagonals: A decagon has 35 diagonals. The formula for the number of diagonals in an n-sided polygon is n(n-3)/2.

  • Area: The area of a regular decagon with side length a can be calculated using the formula: Area = (5/2) * a² * [√(5 + 2√5)]

  • Symmetry: A regular decagon has ten lines of reflectional symmetry and rotational symmetry of order 10 (it can be rotated in 36° increments and still look the same).

These are some of the key properties of a decagon. The specifics will depend on whether it's a regular or irregular decagon.