A polygon is a plane geometric figure consisting of at least three vertices (or corners) and edges connecting them into a closing loop. It can also refer to the closed region bounded by the edges, so a polygon can have geometric properties associated with area. Wolfram|Alpha has the ability to recognize several flexible input forms for multiple types of polygons and to compute their properties, including diameter, perimeter, interior angle, etc.
Compute one specific property or multiple properties given a triangle.
Compute one specific property or multiple properties given a regular n-gon.
Compute properties of parallelograms, rectangles and other quadrilaterals.