Government of Alberta
Learn alberta.ca: Mathematics Glossary: Acute Triangle
Get a visual and animated definition of what an acute triangle is, as well as examples of acute angles in the real world. [Requires Java.]
Wolfram Research
Wolfram Math World: Acute Triangle
This MathWorld site gives a short discussion on acute triangles with links to related terms and topics. The site offers a discussion on the least number of acute triangles to compose various polygons, and a discussion on the relationship...