## Types of Triangles

#### TRIANGLES

This lesson covers the following types of triangles:

- Isosceles Triangles
- Equilateral Triangles
- Right-angled Triangles

#### 1. Isosceles Triangles

A triangle that has two equal sides is an

**isosceles triangle**.
Each triangle above has two equal sides.

Hence, they are all isosceles triangles.

Hence, they are all isosceles triangles.

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

**Trivia:**

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

#### 2. Equilateral Triangles

A triangle that has all equal sides is an

**equilateral triangle**.
Each triangle above has all 3 sides of the same length.

Therefore, they are all equilateral triangles.

Therefore, they are all equilateral triangles.

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

**Trivia:**

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

#### 3. Right-angled Triangles

A

Each triangle above has one angle that is a right angle, that is, 90°.

So, they are all right-angled triangles.

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