Explanation:
Rectangle
In Euclidean plane geometry, a rectangle is any quadrilateral with four right angles. The
term "oblong" is occasionally used to refer to a non-square rectangle. A rectangle with vertices ABCD would be denoted as ABCD. A so-called crossed rectangle is a crossed
(self-intersecting) quadrilateral which consists of two opposite sides of a
rectangle along with the two diagonals. Its angles are not right
angles.
Formulas
The formula for the perimeter of a rectangle.
If a rectangle has length l and width w
1. It
has area A = lw, (Our
solved example in mathguru.com uses this concept)
2. It has perimeter P = 2l + 2w = 2(l + w),
3. Each
diagonal has length ,
4. When l = w, the
rectangle is a square.
http://en.wikipedia.org/wiki/Rectangle
The above explanation is copied from
Wikipedia, the free encyclopedia and is remixed as allowed under the Creative
Commons Attribution- ShareAlike 3.0 Unported License.