Hello, I am a new programmer and am faced with a problem which I am not
totally sure how to start.  The problem is as follows:

====================================================

Using recursion, compute the area of a polygone.  Cut off a triangle
and use the fact that a triangle with corners (x1,y1), (x2,y2), (x3,
y3) has
area = |(x1)(y2) + (x2)(y2) + (x3)(y1) - (y1)(x2) - (y2x3) - (y3x1)|/2

The program will be testerd by redirecting a text file to its standard
input.  Such a file represent a polygone.  Within a file, each line
contains two (non-scientific notation) floating point number to
indicate the corrdinates of a vertex.
====================================================

My major problem is the recursive thought that it involves, I can
visualize doing this non-recursively quite easily, so if anyone could
offer any advice on how a recursive approach to this would be started I
would be very greatful.

Thanks.