Question about my textbook

[bilius2007]

In example 2, I found that it's saying the scale factor from ZYXW to FGHJ is 5/4, but it must be a reduction since ZYXW is bigger. Shouldn't it be smaller(4/5), because it is a reduction? What do you guys think?

 

[skeeter]

The scale factor cited is correct ...

(big polygon) : (small polygon) = 5 : 4

 

[bilius2007]

But if you're going from ZXYW to FGHJ, 5/4*25 is not 20

 

[Harry_the_cat]

There's a problem with the language.
The ratio of big:small is 5:4.
It's not about "going from" big to small.

 

[Dr.Peterson]

In example 2, I found that it's saying the scale factor from ZYXW to FGHJ is 5/4, but it must be a reduction since ZYXW is bigger. Shouldn't it be smaller(4/5), because it is a reduction? What do you guys think?

I can see how you can read it as being wrong, but look carefully at the wording:



It does not say, as you misquoted it, "the scale factor from ZYXW to FGHJ", which might indeed suggest the factor you would multiply by to change ZYXW to FGHI, but "the scale factor of ZYXW to FGHJ" which means the ratio of (each side of) ZYXW to FGHI (5:4 being also written as 5/4).

In particular, you may want to think of what they wrote as "the scale factor of ZYXW relative to FGHJ", meaning that (sides of) ZYXW are each 5/4 of the corresponding sides of FGHI.

The wording can be tricky; but then, that is true of any prepositions.

 

[bilius2007]

Thank you so much! I really understand it now!