
 SparkNotes: Special Triangles: Classifying Triangles 
  When triangles are classified according to the lengths of their sides, they fit into one of three categories: scalene, isosceles, or equilateral. 
  When triangles are classified by their angles, they fit into one of four categories: acute, obtuse, right, or equilateral. 
  If a triangle has one obtuse angle (remember that one is the maximum number of obtuse angles a triangle can have), it is an obtuse triangle. 
 www.sparknotes.com /math/geometry2/specialtriangles/section1.html (376 words) 
