In
geometry, a
quadrilateral is a
polygon with four sides and four vertices. Quadrilaterals are further classified as follows:
- Trapezium?: two of the opposite sides are parallel?.
- [Isosceles trapezium]?: two of the opposite sides are parallel, the two angles incident with each side are equal.
- Parallelogram?: opposite sides have equal length, opposite sides are parallel, opposite angles are equal.
- Kite?: two adjacent sides have equal length, the other two sides have equal length, opposite angles are equal.
- Rhombus?: four sides have equal length, opposite sides are parallel, opposite angles are equal.
- Rectangle?: opposite sides have equal length, opposite sides are parallel, each angle is a right angle.
- Square (regular quadrilateral): four sides have equal length, opposite sides are parallel, each angle is a right angle.
Illustration needed.
Also the name of a group of fortresses in Italy.