1. Similar Figures

2. Congruent Figures
In order to be congruent, two figures must be the same size and same shape.

3. Similar Figures
Similar figures must be the same shape, but their sizes may be different.

4. SIZES
Although the size of the two shapes can be different, the sizes of the two shapes must differ by a factor. 4 2 6 6 3 3 1 2

5. Similarity Transformation-Vocabulary
a dilation is a transformation in which a figure and its image are similar
the ratio of the new image to the original figure is called the scale factor
a dilation with a scale factor greater than 1 is called an enlargement
a dilation with a scale factor less than 1 is called a reduction

6. Enlargements
When you have a photograph enlarged, you make a similar photograph.

7. Reductions
A photograph can also be shrunk to produce a slide.

8. Determine the length of the unknown side.15 12 ? 4 3 9

9. Determine the length of the unknown side.? 2 24 4

10. Sometimes the factor between 2 figures is not obvious and some calculations are necessary.15 12 8 10 18 12

11. When changing the size of a figure, will the angles of the figure also change?40 70 ? ? 70

12. Find the length of the missing side.50 ? 30 6 40 8

13. If you know how tall you are, then you can determine how tall the tree is.
6 ft
10 feet
2 feet

14. Similar Figures
So, similar figures are two figures that are the same shape and whose sides are proportional.

15. 1) Determine the missing side of the triangle.? 9 5 3 4 12

16. 1) Determine the missing side of the triangle.15 9 5 3 4 12

17. 2) Determine the missing side of the triangle.36 36 6 6 4 ?

18. 2) Determine the missing side of the triangle.36 36 6 6 4 24

19. 3) Determine the missing sides of the triangle.39 ? 33 ? 8 24

20. 3) Determine the missing sides of the triangle.39 13 33 11 8 24

21. 4) Determine the height of the lighthouse.? 8
2.5 10

22. 4) Determine the height of the lighthouse.32 8
2.5 10

23. 5) Determine the height of the car.? 3 5 12

24. 5) Determine the height of the car.
7.2 3 5 12