# Can an equilateral triangle also be isosceles?

Jun 4, 2018

Yes; in fact an equilateral triangle must be isosceles.

#### Explanation:

The definition of an isosceles triangle is that two of its sides have equal lengths; the case where all three sides have equal lengths is not excluded.

The definition of an equilateral triangle is that all three sides are of equal length; therefore any two sides are of equal length; and, therefore an equilateral triangle is isosceles.

Jun 4, 2018

See below.

#### Explanation:

So before we start answering the question, let start by listing the properties of both equilateral and isosceles triangle.

Equilateral triangle:
- All sides are the same length
-All angles have the same measurement

Isosceles Triangle:
-2 sides have the same length
- 2 angles have the same measurement

An equilateral triangle can be an isosceles triangle IF one of the sides has a different length than the rest and the angle measurement is different.