Just an observation while
going over the geometry concepts esp. on quads:

A pair of parallel sides mean diagonals bisect each other.
also, having equal length sides imply diagonals are perpendicular -
though it's not the case with a square.

Could you confirm if I've got this right, please?
Thank you.

If we have two pairs of parallel sides (square, rectangle, parallelogram, rhombus) then the diagonals bisect each other.
However, if we only have one pair of parallel sides, as we do in a trapezoid, we don't necessarily have bisecting diagonals.

Equal length sides doesn't imply perpendicular diagonals, though.
This IS the case in a square, where the diagonals are perpendicular, equal, and bisect each other.
It is the case in a rhombus, where the diagonals are perpendicular and bisect each other, but aren't equal to each other.

Everything you need to know on this is in the Geometry text on page 17...

Valerie BRowning
Veritas Prep