1. Math CC7/8 – Oct. 24 Learning Log: Topic: Similarity & Ratios
Things Needed Today (TNT):
Pencil/Math Notebook
Math Book –pg. 80
Labsheet 4.2
Learning Log:
Topic: Similarity & Ratios
HW: SS pg. 90 #1, #42 & #43
pg. 94 #17-22

2. What’s Happening?
S&S 4.1 & 4.2
Begin HW?

3. SS p. 80

5. 10 cm
8 cm

6. Equivalent ratios can be express with equations.
What do you notice about the height-to-width ratios?
The comparisons “10 to 8” & “5 to 4” are equivalent ratios.
Equivalent ratios are like equivalent fractions.
***Ratios are often written in fraction form.***
Equivalent ratios can be express with equations.
A proportion is an equation stating two ratios are equal! 10 8 5 4 = = 8 4 10 5

9. A, B, and C are similar!
Pg. 82

10. Short Long Pg. 82 Similar rectangles have the SAME ratio!
Non-similar rectangles have different ratios!

11. Scale Factor:
B to A = 2
B to C = 1.5
C to A =
Pg. 82
This tells you how many times as great each side length and perimeter are

12. Ratio of short side to long side Pg. 83
Scale Factor:
B to A = 2
B to C = 1.5
C to A =
Ratio of short side to long side
Pg. 83
Add to notes
Similar figures have a constant scale factor and their ratios of corresponding side lengths will be equivalent.
The scale factor gives the amount of stretching (or shrinking) from the original figure to the image.
The ratio of adjacent side lengths within a figure gives an indication of the shape of the original figure (and image), since it compares measures within one figure.

13. Hmmmmmmm.

16. Labsheet 4.2 A, C, and D are similar!
Which shapes are similar? Explain your reasoning.
A, C, and D are similar!

17. “Middle” Short Long Short 9 12
The corresponding ratios of adjacent side lengths of similar triangles are equal!
Typically, non-similar triangles possible ratios of two sides will be different values.

18. Special Notes
For triangles to be similar ALL corresponding ratios must be equivalent.
For triangles to be non-similar, AT LEAST one pair must be non-equivalent

19. Scale Factor
This tells you how many times as great each side length and perimeter are

20. Short
Long
Short
“Middle”
Scale Factor 9 12

21. Add to notes if you didn’t before
Similar figures have a constant scale factor and their ratios of corresponding side lengths will be equivalent.
The scale factor gives the amount of stretching (or shrinking) from the original figure to the image.
The ratio of adjacent side lengths within a figure gives an indication of the shape of the original figure (and image), since it compares measures within one figure.

22. Can you answer these questions now?
Answer these questions in your notebook

23. Homework
SS pg. 90 #1, #42 & #43
pg. 94 #17-22