<img src="https://d5nxst8fruw4z.cloudfront.net/atrk.gif?account=iA1Pi1a8Dy00ym" style="display:none" height="1" width="1" alt="" />
Skip Navigation
Our Terms of Use (click here to view) have changed. By continuing to use this site, you are agreeing to our new Terms of Use.

8.9: Composite Area and Change of Dimensions

Difficulty Level: At Grade Created by: CK-12
Turn In

Editor’s note: This lesson has very limited material supported by CK-12. Please refer to the Geometry Access Reader for additional materials.

Learning Objectives

  • Use similarity to generalize the results.


We know that all circles are similar to each other.

Suppose a circle has a radius of \begin{align*}r\end{align*} units.

  • The scale factor of this circle (with radius \begin{align*}r\end{align*} ) and the circle with radius 1 is:

\begin{align*}r : 1, \quad \frac{r}{1}, \quad \text{or just} \quad r\end{align*}.

  • You know how a scale factor affects area measures:

If the scale factor is \begin{align*}r\end{align*}, then the area is \begin{align*}r^2\end{align*} times as much.

Reading Check:

1. Explain how we know that all circles are similar to each other.

(Hint: Think about similar measurements that circles may have.)





2. If the scale factor of a circle is \begin{align*}r\end{align*}, how does this relate to a circle’s area?





Notes/Highlights Having trouble? Report an issue.

Color Highlighted Text Notes
Please to create your own Highlights / Notes
Show More

Image Attributions

Show Hide Details
8 , 9 , 10
Date Created:
Jan 13, 2015
Last Modified:
Jan 13, 2015
Save or share your relevant files like activites, homework and worksheet.
To add resources, you must be the owner of the section. Click Customize to make your own copy.
Please wait...
Please wait...
Image Detail
Sizes: Medium | Original