Question

The perimeter of an equilateral triangle is 45cm.

Answer 1

I think you need more specifics to your problem. Are you trying to solve for the length of the side of the triangle? If so, what do we know about the sides of an equilateral triangle (it is the definition of this kind of triangle)? Then, what is perimeter in general? Can you figure out an equation in terms of the side of a triangle of this type? Then use that you know the perimeter to find the side length.