Re: Triangle with more than 180 degrees-

*** wrote:
Hero wrote:


> Let me see, how much sense non-euclidian mathematicians are making.
> They claim, they negate the fifth postulate of Euclid,
> given in here:
>http://mysite.du.edu/~etuttle/classics/nugreek/lesson17.htm
>
> And they claim there is an elliptic space, where Euclid's fifth is not
> valid, but a negation of it.
> That is the space of the very first posting in here.
> But when i look at their models of elliptic geometry, i only see that
> any two of their 'straight lines' always intersect,
> so they do intersect, when they have a sum of angles less than two
> right ones with a third 'straight line'.
> Where is the negation?

The fifth postulate. Given a point and a (straight) line, there is a
(stright) line through the point that does not intersect the given line.
If any two straight lines do intersect, the fifth postulate does not hold.
Or do you think that postulate holds when any two straight lines do
intersect?


Did You ever read the postulates of Euclid?
I gave You a link and here is another one:
http://aleph0.clarku.edu/~djoyce/java/elements/elements.html

And so the question - not only to You -
where is the negation?

With friendly greetings
Hero
.