I've been sent a paper by an amateur mathematician showing a link between a perfect Euler brick, and orthodiagonal quadrilaterals. Is a connection between these well-known? Obvious? Or is this of at least some interest, even if it's just a simple observation? As always, if it's new or at all significant, the mathematician in question is keen to have their name attached to it, but can't get anyone interested, so I'd like to know people's reactions to the idea that these things are related. To save you looking them up: Perfect Euler brick: a cuboid with integer sides, face diagonals, and long diagonal. Orthodiagonal Quadrilateral: A quadrilateral whose diagonals cross at right angles. Best regards, Colin -- The power of accurate observations is commonly called cynicism by those who haven't got it. -- George Bernard Shaw