 A "regular tetracontagon" is represented by Schläfli symbol {40} and can also be constructed as a truncated icosagon, t{20}, which alternates two types of edges.Furthermore, it can also be constructed as a twice-truncated decagon, tt{10}, or a thrice-truncated pentagon, ttt{5}.One interior angle in a regular tetracontagon is 171°, meaning that one exterior angle would be 9°.