In details

Quads


Definition

Quadrangle It is a four-sided polygon.


Quadrangle A B C D

In a quadrangle, two sides or two nonconsecutive angles are called opposites.


Elements

In the figure below, we have:


Quadrangle A B C D

Vertices: A, B, C, and D.
Sides:
Diagonals:

Internal angles or angles of
ABCD quad: .

Comments:

  1. Every quad has two diagonals.

  2. The perimeter of a quadrilateral ABCD is the sum of the measurements on its sides, ie AB + BC + CD + DA.

Concave and Convex

The quads can be convex or concave. A quad is convex when the line joining two consecutive vertices does not find the side formed by the two other vertices.


Convex Quad


Concave Quad

Next: Sum of Inner Angle Measurements