You can put this solution on YOUR website!
I'm just wondering: are there any actual triangular lake front lots out there? It'd be cool to see.
Anyways, let's denote x as the shortest side.
Shortest side = x
One side = 200 + x
Third Side = 400 + x
Perimeter of a Triangle = Sum of All sides
1800 = x + 200 + x + 400 + x
So all you need to do now is to solve for x, and than based on x, add the appriopriate integer to get the different sides.
Write back if you need help. Good luck!