[MWForum]Calling mathcats: geometry help please

[Daniel Ajoy]

On 11 Aug 2004 at 17:41, Jeff Knope wrote:

> Googling around, there appear to be a few ways to go about it. The most simple and direct of them
> appears to be the algebraic solution of 2 simultaneous equations. Trouble is, as I examine my own
> (weak) processes for doing that, I find I'm doing lots of visual scanning for opportunities to
> algebraically reduce the expressions. It's a kind of intuitive process I haven't the faintest idea
> how to reduce MW procedures.
> 

There is a big problem with approaching intersections of lines
with 2 simultaneous equations ala:

y1 = a x1 + b    (line 1)

y2 = c x2 + d    (line 2)

(and still, textbooks don't have any admonition)

The problem is this:

How do you represent the line that goes through [0 0] [0 1]?

or any vertical line for that matter?

A second problem is to find a not-too-cumbersome way to
termine when lines do intersect, but the line segments
between x1 and x2, and x3 and x4 do not. For example:

[[[1 1] [5 5]]
 [[3 1] [6 5]]]


Daniel
OpenWorld Learning (OWL)
http://mia.openworldlearning.org