Decagon

A decagon is a polygon with 10 sides and 10 vertices.

Regular Decagon

A regular decagon is a polygon with 10 equal sides and angles.

Angles of the Decagon

The sum of interior angles of a decagon = (10 − 2) · 180° = 1,440°

The value of an interior angle of a regular decagon is: 1,440º : 10 = 144º

The central angle of a regular decagon measures: 360º : 10 = 36º

Diagonals of the Decagon

The number of diagonals in a regular decagon = 10 · (10 − 3) : 2 = 35

Perimeter of a Regular Decagon

Perimeter = 10 · l

Area of a Regular Decagon

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