1. Congruent and Similar Shapes
Apply the relationship between ratios, equivalent fractions and percents to solve problems in various contexts

2. I can… Identify congruent and similar figures
Find missing sides and angles of congruent and similar figures
Self Assessment
5- I can do it without help & teach others.
4- I can do this with no help, but I don’t know if I can explain it.
3- I can do this with a little help.
2- I can do this with a lot of help!
1- I don’t have a clue.

3. What makes a pair of shapes “congruent”?
Same angles
Same side lengths
Can be rotated or a mirror image
A cut-out of one shape will always fit exactly over the other

4. Which of these shapes are congruent to the yellow one?1 4 3 2 5 7 8 6

5. Which of these shapes are congruent to the yellow one?1 4 3 2 5 7 8 6

6. Which of these shapes are congruent to the yellow one?1 4 2 3 8 5 6 9 7

7. Which of these shapes are congruent to the yellow one?4 1 2 3 8 6 5 9 7

8. Using Corresponding Part
When 2 figures are congruent the corresponding parts are congruent. (angles and sides)
If Δ ABC is  to Δ XYZ, which side is  to BC? YZ Y B X A Z C

9. Using Corresponding Part
If Δ ABC is  to Δ XYZ, which side is  to AB? XY Y B X A Z C

10. Using Corresponding Part
If Δ ABC is  to Δ XYZ, which angle is  to angle Z? Z Y X C B A C

11. What makes a pair of shapes “similar”?
Same angles
Sides in the same proportion
Can be rotated or reflected
One is an enlargement of the other
Scale factor gives degree of enlargement:
Scale factor 2 → size is doubled
Scale factor ½ → size is divided by 2
Scale factor 1 → size doesn’t change → congruent too

12. Which of these shapes are similar to the yellow one?1 4 3 2 5 7 8 6

13. Which of these shapes are similar to the yellow one?1 4 3 2 5 7 8 6

14. Using similarity 9 12 6 = a 12 • 6 = 9a 72 = 9a 9 = 9 8 = a
Since shapes are similar, their sides are in the same proportion
6 = a
9 12
9cm
12cm
12 • 6 = 9a
72 = 9a
6cm
9 = 9 a
8 = a

15. These figures are similar. Find the values of x.y
3 = 6
4 x
4 • 6 = 3x
24 = 3x
3 = 3
8 = x

16. These figures are similar. Find the values of y.
8 cm y
50o

17. I can… Identify congruent and similar figures
Find missing sides and angles of congruent and similar figures
Self Assessment
5- I can do it without help & teach others.
4- I can do this with no help, but I don’t know if I can explain it.
3- I can do this with a little help.
2- I can do this with a lot of help!
1- I don’t have a clue.

18. Congruent and Similar Figures
9.7 Notes
Congruent and Similar Figures
Congruent: same size and shape
have congruent corresponding angles and sides
Similar: same shape, but different size
have congruent angles, but MUST use proportions to find the side lengths