TRIANGLES: Types of Triangles

Isosceles Triangle

A triangle that has two equal sides is an isosceles triangle.


We show two or more equal sides by putting a small slash across them.

Each of the triangles above has two equal sides. Hence, they are all isosceles triangles.

Trivia:

If you measure the angles of an isosceles triangle you will notice that the angles opposite its equal sides are equal.


Equilateral Triangle

A triangle that has all equal sides is an equilateral triangle.


We show an equilateral triangle by putting a small slash across each of its 3 sides.

Each of the triangles above has all 3 sides of the same size. Therefore, they are all equilateral triangles.

Trivia:

If you measure the angles of an equilateral triangle you will notice that each of its angles is equal to 60°.


Right-angled Triangle

A right-angled triangle, as the name suggests, is a triangle that has one angle that is equal to 90°.



Each of the triangles above has one angle that is a right angle or is 90°. So, they are all right-angled triangles.

Trivia:

If you measure the other two angles of a right-angled triangle you will notice that their sum is equal to 90°.