DECAGON

In geometry, a 'decagon' is any polygon with ten sides and ten angles, and usually refers to a regular decagon, having all sides of equal length and all angles equal to 144°, therefore making each angle of a regular decagon be 144°. Its Schläfli symbol is {10}.
The area of a regular decagon of side length ''a'' is given by
:

Contents

Construction

See also

External links

Construction

A regular decagon is constructible with a compass and straightedge.
#Complete steps 1 though 6 of constructing a pentagon.
#Extend a line from each corner of the pentagon through the center of the circle made in step 1 of constructing a pentagon to the opposite side of that same circle.
#The five corners of the pentagon constitute every other corner of the decagon. The remaining five corners of the decagon are those points where the lines of step 2 cross the original circle (but not a pentagon corner).

See also

★ decagonal number

★ Gambrel

External links

★

★ Definition and properties of a decagon With interactive animation