In which quadrilateral are the diagonals always congruent?

parallelogram

trapezoid

square

rhombus

Question

In which quadrilateral are the diagonals always congruent?

       parallelogram

       trapezoid

       square

       rhombus<i think it might be a rhombus not sure though

debbieg · Answer

http://www.mathsisfun.com/quadrilaterals.html

debbieg · Answer

|dw:1380743128370:dw|

debbieg · Answer

|dw:1380743178346:dw|

anonymous · Answer

what do u thin it is then?

anonymous · Answer

think*

debbieg · Answer

I KNOW what it is. :) What do YOU think it is?

Look at that link I posted, see what each of your options looks like.

ask which shape CANT have non-congruent diagonals?

debbieg · Answer

hey, is it possible to have more than one answer? I just noticed, I think that TWO of these always have congruent diagonals.

anonymous · Answer

my second guess would be a square

debbieg · Answer

Yes, definitely a square. all sides and angles are equal, so the diagonals have to be equal.

debbieg · Answer

OK, never mine - that's the only one. For a minute I was thinking it would hold for one of the other choices too, but I realize now that I was mistaken. Only true for a square. 

Consider why:
All the sides and angles are congruent, so the diagonals are both hypotenuses of congruent right triangles.