Definition-A scalene triangle is a triangle in which no two sides are congruent.

Definition-An isoceles triangle is a triangle in which at least two sides are congruent.

Definition-An equilateral triangle is a triangle in which all sides are congruent.

Definition-An equiangular triangle is a triangle in which all angles are congruent.

Definition-An acute triangle is a triangle in which all angles are acute.

Definition-A right triangle is a triangle in which there is a right angle.

Definition-An obtuse triangle is a triangle in which there is one obtuse angle.

Example:
For an example please go to SECTION 3.5. Isoceles triangle.