How can you prove a triangle is in equilateral triangle

An equilateral is a shape with two or more sides with the same length.

So, to prove a triangle is an equilateral shape is that you have the bottom straight and you have to make the both sides of the triangle meet each other so they have to be the same size, of course.

You can also prove they are equilateral shapes because you can use a ruler to measure the lengths.

I hope this helped! =)