A little help, please...

I have a C++ assignment due on Monday based on Hero's formula. After about an hour of working through errors, I got it to compile, but the answer it gives for the area of every triangle is 4.17693e-20. I'm required to use all of the included functions (and honestly, my understanding of functions, especially what goes in the parentheses after them is quite limited). I think the problem lies in the CalculateArea and TestforTriangle functions, but I can't figure out how to make it work right. Any assistance would be highly appreciated.

Posting the code was less than effective -- here's a link to it, without the #includes at the top because HTML didn't like them, and I wasn't in the mood to look up how to do that: http://www.anzwers.org/free/dromarchive/heroprogram.html