Triangles can be classified in the following manner:

  1. By ANGLES
    1. acute triangle- a triangle with 3 acute angles
    2. right triangle- a triangle with one right angle
    3. obtuse triangle- a triangle with one obtuse angle
    4. equiangular triangle- a triangle with 3 congruent 60 degree angles
  2. By SIDES
    1. scalene triangle- a triangle with no congruent sides
    2. isosceles triangle- a triangle with at least 2 congruent sides
    3. equilateral triangle- a triangle with 3 congruent sides

  1. All equilateral triangles are equiangular.
  2. All equiangular triangles are equilateral.
  3. A right triangle will have 1 right angle and 2 acute angles.
  4. An obtuse triangle will have 1 obtuse triangle and 2 acute angles.
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