Question: I was recently given a challenge in my Algebra class. My teacher wanted to know about a right angle. He said he would give five bonus points to the person that could bring in information. (I know five bonus points may not seem like a lot but in this class, they are.) I looked on this site and I found out why it was called a right triangle, but my teacher want to know where did that theory come from. I was wondering too... not just because of the bonus points.

AshLee,

I assume that you have looked at Haragauri's answer to a previous question. The other place where I found some information was on Earliest Known Uses of Some of the Words of Mathematics, a site maintained by Jeff Miller. Go there and look under R for the word right.

Jeff also has a web site called Earliest Uses of Various Mathematical Symbols. I looked there under geometry for right angle and found a note to say that the symbol was used by Papus.

Penny