Their perimeters are in the same ratio.
The sacle factor between two shapes is the same as the ratio of their perimeters.
All polygons
"18 perimeters" is is a meaningless phrase since there are no units of measurement. It is like asking how tall are 18 heights?
There is no particular reason. In fact, in general, two shapes will have different areas or perimeters or both.
3D objects do not have perimeters.
yes
No, squares do not represent perimeters.
There is no direct relationship
Yes.
Yes
5:3