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Session 8, Part A:
Scale Drawings
In This Part: Finding a "Good Copy" | Doubling the Coordinates | Distances and Angles
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Here's a picture of a cat's head (it's really a polygon!) on a coordinate grid:
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Problem A4 |  |
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? |
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Problem A5 | |
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. |
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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
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