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Learning Math Home
Geometry Session 8: Similarity
 
Session 8 Part A Part B Part C Homework
 
Glossary
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Session 8 Materials:
Notes
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Video

Session 8, Part A:
Scale Drawings

In This Part: Finding a "Good Copy" | Doubling the Coordinates | Distances and Angles

Here's a picture of a cat's head (it's really a polygon!) on a coordinate grid:


 

Problem A4

Solution  

a. 

Copy the picture of the cat's head onto a piece of graph paper, and find the coordinates of each point.

b. 

Multiply the coordinates of each point by 2, creating points A' through H'. Use the rule (x,y) (2x,2y).

c. 

Plot these new points on the same grid, and connect them in the same order.

d. 

Is your new figure similar to the original picture? How do you know?


 

Problem A5

Solution  

Explain why, if you want to create a similar figure with sides twice as long as the original, you don't double all the angles as well.


 
 

The ratio between corresponding sides of the cat's head is called the ratio of proportionality. Since we made the sides twice as long, the ratio of proportionality is 2. Note 2


 

Problem A4 adapted from IMPACT Mathematics, Course 3, developed by Educational Development Center, Inc. © 2000 Glencoe/McGraw-Hill. Used with permission. www.glencoe.com/sec/math

Next > Part A (Continued): Distances and Angles

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