十边形是几何学上所有有10条边和10只角的多边形。

正十边形是十边等长、十角等大的多边形。内角为144°。若边长为，面积。尺规作图可先在圆形内制作正五边形，再将各边二等分线延伸至圆周以完成正十边形的顶点。

In geometry, a decagon is a ten-sided polygon or 10-gon.

A regular decagon has all sides of equal length and each internal angle will always be equal to 144°. Its Schläfli symbol is {10} and can also be constructed as a truncated pentagon, t{5}, a quasiregular decagon alternating two types of edges.