Geometry and Triangles
This site, called Math for Morons, can help with many concepts with which you might be struggling. The link below is called "Isosceles and Equilateral Triangles."
http://library.thinkquest.org/20991/geo

Benjamin Bannecker
Did you notice the Historical Perspective at the beginning of this section? Euclid is one of the most famous mathematicians from antiquity. If you want some additional information, you can check out this site.
http://www-history.mcs.st-and.ac.uk/~history/Mathematicians/Banneker.html