Triangles are 3 sided polygons. The 3 different types of triangles classified by angles are: Obtuse triangles with 1 obtuse angle, Acute triangles with all of the angles less than 90 degrees, and right triangles which have 1 right angle. The 3 different types of triangles classified by sides are: Equilateral triangles which have 3 equal sides, isosceles triangles which have 2 equal sides, and scalene with no equal sides.
