jmc

If two similar triangles have side ratios of $r:1,$ the ratio of their areas must be $r^2:1.$ That means that when a triangle is tripled to form a new triangle, the new triangle has 9 times the area of the original. That means the original triangle must have an area of $\frac{54{\text{ ft}}^2}{9}=\boxed{6}{\text{ ft}}^2.$