If two polygons are similar how can you find the scale factor from one polygon to the other?

If two polygons are similar, then the ratio of a side-length of one of them
to the length of the corresponding side of the other one is the same number
for every pair of sides.  All you need to do is find one pair of corresponding
sides, then find the ratio of their lengths, and there's your scale factor.

I’m not sure about that