perplexus.info :: Just Math : Squares and Rectangles

Squares and Rectangles (Posted on 2004-01-21)

There is a grid of 20 squares by 10 squares. How many different rectangles are possible?
(Note that square is a rectangle).

See The Solution Submitted by Ravi Raja

Rating: 2.0000 (5 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)

re(2): Nodes

| Comment 7 of 22 |

(In reply to re: Nodes by Sam)

Not silly at all...

He counted all diagonals twice... so, yes divide by 2 (and we get the number of unique diagonals).

But then each rectangle has TWO of those diagonals... so divide by 2 again (to get the number of unique rectangles).

Posted by SilverKnight on 2004-01-21 11:46:36

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