in a chessboard how many rectangles are there whose area is equal to 3 times the area of a small square

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- Jan 4th 2011, 11:04 AMprasumchessboard problem
in a chessboard how many rectangles are there whose area is equal to 3 times the area of a small square

- Jan 4th 2011, 11:14 AMArchie Meade
The rectangles require 3 consecutive squares in a straight line.

Each of the 8 rows contains 6 sets of 3 horizontally adjacent squares.

That's 6 rectangles per row over 8 rows.

The rectangles in the columns can be counted in the same way.

There are no diagonal rectangles. - Jan 5th 2011, 02:00 AMprasum