Originally Posted by ghostrider

I don't know about books, but Quilt University has a Math for Quilters class that's next offered starting April 27th. Three lesson class for $27, taught by Dena Crain (she's great, I had her for a different class awhile ago).
http://www.quiltuniversity.com/catalog.htm
Class description is down at the bottom, under 'Other'. It's one of their most popular classes.

Victoriana Quilt Designs also offers several free PDF charts covering quilters math, including triangles of all types.
http://www.victorianaquiltdesigns.co...rts/Charts.htm