This isn't a thread about quantum electrodynamics so those of u thinking it is can leave now !!!

Just wondering, what does QED stand for at the end of proven theorems?! My maths teacher in school was a funny guy and he used to say 'quite easily done' at the end of trigonometrical theorems but what is it exaclty. I remember being told ages ago but I've forgotten now. I think it is Latin is it?

Quod erat demonstrandum.

Originally posted by (Q)
Quod erat demonstrandum.

And what does that mean do u know?

Originally posted by John Connellan
And what does that mean do u know?

it means "that which was to be proved"

quod is a relative pronoun in the neuter so, which, or that.

erat = was
demonstrandum = the future participle of demonstare = to be proved

Thank you guys!