1. Stretching and Shrinking
Students will be able to use scale factor to determine distances, students will be able to find unknown heights using similar figures.

2. Investigation 4: Similarity and Ratios

3. Homework Investigation 4
Page 90 A 1,3,4-7, 12,14,16,18 B 16,18,40,42,43,

4. Warm Up

5. 4.1 Ratio within Similar Parallelograms
What information does the ratio of adjacent side lengths within a rectangle give you?

6. Terms
Ratios comparison of two quantities, such as 2 lengths Equivalent Ratio’s like equivalent fractions, simplify down to the same value Proportion an equation setting two ratios equal

7. Problem 4.1 page 82
Watch video A,B,C Adjacent sides Sides that share a vertex or corner

8. Warm Up

9. 4.2 Ratios within similar Triangles
For a pair of triangles, if the measure of corresponding angles are equal, how can you use ratios of side lengths to determine whether or not the triangles are similar?

10. Problem 4.2 pg 85
When setting up ratios make sure you are comparing corresponding sides, short to short and long to long Pg 84 Who is correct? Prob 4.2 A,B,C,D

11. Warm Up

12. 4.3 Finding Missing parts
If two shapes are similar, how can you use information about the shapes to find unknown side lengths, perimeters and areas?

13. Prob 4.3 pg 86
2 methods Scale factor from one figure to the other Use ratios of the side lengths within each figure A,B,C,D

14. Warm Up

15. 4.4 Using Shadows to find height
How can you use similar triangles to estimate the heights of tall objects?

16. Problem 4.4 pg 88
Watch Video Answer questions on page 88 Discuss the shadow method Lab to measure objects

17. Essential questions
What information does the ratio of adjacent side lengths within a rectangle give you?
For a pair of triangles, if the measure of corresponding angles are equal, how can you use ratios of side lengths to determine whether or not the triangles are similar?
If two shapes are similar, how can you use information about the shapes to find unknown side lengths, perimeters and areas?
How can you use similar triangles to estimate the heights of tall objects?