A pentagon is a [b]5-sided polygon[/b].[br]If its sides are [b]equal[/b] to each other, it is a [b]regular[/b] pentagon. Otherwise, it is called an [b]irregular[/b] pentagon.[br]Every pentagon can be divided into three triangles without any of them collapsing on one another.[br]That is why, the [b]sum of the interior angles[/b] of a [b]pentagon[/b] is [math]180\times3=540^\circ[/math]