Which expressions are equivalent to 2e*f?

2 x e x f = e x 2 x f = f x 2 x e

This is because of the commutative property in multiplication.

The order in which you multiply numbers won't change the value of their product.

A triangle is a polygon with three edges and three vertices. It is one of the basic shapes in geometry. A triangle with vertices A, B, and C is denoted. In Euclidean geometry any three points, when non-collinear, determine a unique triangle and a unique plane. This article is about triangles in Euclidean geometry except where otherwise noted