1. Chapter 2 Justification and Similarity
2.2 Students will be able to perform dilations and determine common qualities of the two figures. Students will identity the properties of similar figures.

2. 2.21 Dilations Make a point in the lower left corner of the paper
Draw a polygon to the right and up from the points
Using the 2 rubber bands
Place one end on the point
Stretch rubber band so knot connecting the rubber bands is on the figure
Put pencil inside loop of second rubber band and draw on the paper as your trace the shape with the knot
Repeat with 2 rubber bands

3. Dilation Making a figure grow or shrink by a scale factor
How to make a dilation
Write coordinates of all the points
Multiply all the points by the scale factor
Plot all new coordinates and connect Or
From point of dilation draw a ray through all points in the object
Do scale factor to the length of the segment from point to vertices

4. Dilation Finding the scale factor and point of dilation
Write down ordered pairs of original and new
Take x value of new and divide by x value of original this will give you scale factor
Draw a line through corresponding vertices and see where they intersect to get point of dilation

5. Similar Polygons
Shame shape but different size Work through 2-48 What did you notice Work through 2-49 How can we determine if figures are similar All corresponding angles are congruent, but sizes of sides are different All corresponding sides use the same scale factor or same proportion

6. Similar Polygons
To prove them similar AAA SSS SAS ASA If corresponding angles are congruent and corresponding sides are proportions Proof is written similar other than proving sides proportional

7. Homework
Worksheet on Dilations Worksheet on similar polygons