There is a grid of 20 squares by 10 squares. How many different rectangles are possible?
(Note that square is a rectangle).
(In reply to
Question by Penny)
Well, those points do not a rectangle make.
But, I think, you're talking about rectangles that aren't ON the integral lattice lines, such as (1,2) (2,1) (4,3) (3,4).
And the previous/posted solutions do not take those into account.
I think non-lattice rectangles are beyond the scope of this problem (or it would have mentioned rectangles determined by the lattice points, rather than than referencing a 20 by 10 grid).
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That being said, your related question *is* a rather interesting side note... and can be solved similarly to the asked problem (although a little more complicated).
- SK
re: Question
