praet i wud like to corret here.
The Diagonals are equal in length for both square and rectangle..The only thing different is the length of side.
This may not be true. Have u seen a "kite"... in india people fly a lot of it.
A kite is a quadrilateral that can have its diagonals equal and perpendicular to each other at the same time and still its neither a square/rectangle. Or to look at it simply just draw to lines perpendicular to each other and of equal length. Now one line can be moved vertically along the length of another line and at each instance a quad, can be formed by joining the 4 end points of these four lines. Do u see what i am saying...?
Whereas, if all the angles of a quadrilateral are 90 degress it must be a square or a rectangle. And then if it is given that both diagonals are equal. Still i can only say that it must be either square/rectangle (coz both have equal diagonals)
correct me if i am wrong.
-vicky