Inv 1.1 an Introduction.

 Hi All,

Here is an introduction to the Unit.

Stretching and Shrinking

Overview of Ideas

SIMILARITY

Two figures are similar if: (1) the measures of their corresponding angles are equal and (2) the lengths of their corresponding sides increase by the same factor, called the scale factor.

SCALE FACTOR

The number used to multiply the lengths of a figure to stretch or shrink it into a similar image.

A scale factor larger than 1 will enlarge a figure. A scale factor between 0 and 1 will reduce a figure.

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Preview activity:

You will need:

• A ruler

• A pencil

• A blank sheet of paper

1. Draw a rectangle on the paper with whole number side lengths between 1-4 inches

2. Label its corners ABCD

3. Draw a second rectangle similar to the first (ABCD) with a scale factor of ½.  (reduce each side length by ½.  

4. Label its corners EFGH.

5. Draw a right triangle with whole number leg lengths between 1-4 inches

6. Label its corners ABC

7. Draw a second right triangle similar to the first (ABC) with a scale factor of 3.  (increase each of its side lengths by 3. 

8. Label it  DEF.

**Bring the paper to class on Thursday and Friday. We will base our discussion on it.