math
posted by Anonymous .
which of the following have congruent diagonals?
square
rhombus
parallelogram
rectangle
i believe the answer is the square and rectangle.

I think so too.

what about a parallelogram?

Only rectangles (squares included) have congruent diagonals, because all their angles are congruent (90 degrees). If you have angles larger or smaller than 90 degrees it makes the diagonals different lengths.

oh yeah, that's right. Thank you very much!