Question

If the perimeter of ABCDE is 38, find the perimeter of FGHIJ (diagram in the comments)

Answer 1

first find the ratio since they are similar

Answer 2

Okay...

Answer 3

perimeter new/perimeter old=k

Answer 4

So, I'm finding the ratio of the both shapes...?

Answer 5

I'm sorry! I'm not stupid, I just do not understand this at all :/

Answer 6

no you are not stupid,
do you notice that the shapes are similar

Answer 7

Yes

Answer 8

so the ratio is the the same for any similar sides,so the question is which sides are similar

Answer 9

BA and GF
FG and AE
do you agree

Answer 10

Yes

Answer 11

so scale factor k is
\[k=BA/GF=FG/AE\]

Answer 12

\[k=15/10=3/2\]
so scale factor is 3/2

Answer 13

to get perimeter
\[P(new)/P(old)=k\]
\[P(new)/38=3/2\]
\[P(new)=3*38/2=57\]