# Two similar triangles have a scale factor of 1:3. If the perimeter of the smaller triangle is 27, what is the perimeter of the larger?

A "scale factor" means the bigger triangle is bigger by a certain amount. A scale factor of 1:3 means that one triangle is 3 times bigger than the other, for example. So, if the small triangle has a perimeter of 27, the big triangle has a perimeter 3 times as big. Doing the math, $3 \cdot 27 = 81$ - the big triangle's perimeter, then, is 81 units.