Question

Are all equilateral triangles also isosceles triangles?

Answer 1

Yes

Explanation:

Isosceles = at least TWO sides of equal length.
Equilateral = ALL THREE sides of equal length. Therefore, at least two of them must be of equal length.

Answer 2

Yes, all equilateral triangles are also isosceles.

Explanation:

By definition all sides of an equilateral triangle are equal in length and all angles are equal in degree measure.

By definition an isosceles triangle has at least two sides of the triangle of equal measure and the two base angles are equal in degree measure.

Therefore an equilateral triangle is also an isosceles triangle.