Triangles
This lesson reviews the common types of triangles in geometry.
Triangles are three-sided shapes that lie in one plane.
Triangles are polygons that have three sides, three vertices and three angles.
The sum of all the angles in any triangle is 180°.
Classifying Triangles
Triangles can be classified according to the size of its angles. Some examples are right triangles, acute triangles and obtuse triangles.
The lengths of the sides of triangles is another common classification for types of triangles. Some examples are equilateral triangles, isosceles triangles and scalene triangles.
The following figures show the different types of triangles. Scroll down the page if you need more explanations and examples of each type of triangle and how to solve problems involving them.
