Explanation:
Square

A square is a regular quadrilateral

In geometry, a square is a regular quadrilateral. This means that it has four
equal sides and four equal angles (90degree angles, or right angles). A square with vertices ABCD would be denoted ABCD.
Perimeter
and area
The
area of a square is the product of the length of its sides.
The perimeter of a square whose sides have length t is
(Our solved example in mathguru.com uses
this concept)
and
the area is
http://en.wikipedia.org/wiki/Square_(geometry)
Rectangle
In Euclidean plane geometry, a rectangle is any quadrilateral with four right angles. The
term "oblong" is occasionally used to refer to a nonsquare rectangle. A rectangle with vertices ABCD would be denoted as ABCD. A socalled crossed rectangle is a crossed
(selfintersecting) 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, It
has perimeter P = 2l + 2w = 2(l + w), (Our solved example in mathguru.com uses this concept)
2.
Each diagonal has length ,
3.
When l = w, the rectangle is a square.
http://en.wikipedia.org/wiki/Rectangle
The above explanation is copied from
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Commons Attribution ShareAlike 3.0 Unported License.