1. Perimeter and Area of Similar Figures
Geometry
Unit 4, Lesson 4

2. Perimeters of Similar Figures

3. Areas of Similar Figures

4. What we discovered:
If the similarity ratio of two similar figures is a:b, then
The ratio of their perimeters is a:b
The ratio of their areas is a2:b2

5. Example 1
3 in
5 in
The area of the smaller regular hexagon is 30 in2. Find the area of the larger hexagon.
What is the ratio of the corresponding sides?
What is the ratio of the areas?

6. Example 1
3 in
5 in
The area of the smaller regular hexagon is 30 in2. Find the area of the larger hexagon.

7. Example:
The similarity ratio of 2 triangles is 3:2. The area of the larger triangle is 36cm2. Find the area of the smaller triangle.
What is the ratio of the areas?
Set up the proportion:

8. Example:
The areas of two similar triangles are 50cm2 and 98cm2. What is the ratio of their perimeters?
Simplify the ratio then Work Backwards!

9. Example
50 98
REDUCE!
25 49
Find the square root
5 7

10. Example:
The areas of two similar rectangles are 2940 ft2 and 135 ft2. Find the ratios to their perimeters.
Ratio = 14/3