Homework Help

Two soft toys are similar. One toy is three times the height of the other. How much...

user profile pic

tamanimat | Student, Grade 11 | Salutatorian

Posted November 11, 2012 at 7:32 AM via web

dislike 0 like

Two soft toys are similar. One toy is three times the height of the other.

How much more material is required to make it?

Similarity:Volume and surface area of similar solids

1 Answer | Add Yours

user profile pic

tiburtius | High School Teacher | (Level 3) Associate Educator

Posted November 11, 2012 at 1:02 PM (Answer #1)

dislike 1 like

Since the toys are similar the bigger toy does not only have 3 times greater height but also 3 times greater depth and width (if the toys are 3-dimensional). So the volume of bigger toy is 3*3*3=27 times greater. If the toys are 2-dimensional you will get that bigger toy has 3*3=9 times greater surface area.

In mathematics this is called homothetic transformation and ratio k which is in your case k=3. So for similar 2-dimensional objects with ratio k ratio of their surface area is `k^2` and for 3-dimensional objects ratio of their volumes is `k^3.`

For further explenation see e.g. Bruce E. Meserve: Fundamental Concepts of Geometry or one of the links below.

Sources:

Join to answer this question

Join a community of thousands of dedicated teachers and students.

Join eNotes