1. Section 5.1 Perimeter and Area
Name __________________
Section 5.1 Perimeter and Area
Objective: Solve problems involving perimeter and area of triangles and rectangles

2. Notes
A _____________ is an equation that shows a relationship among certain quantities.
Formulas are commonly used in _________.
For examples, the distance around a geometric figure is called the ___________.

3. Key Concept: Perimeter
Rectangle
Triangle
Model
Words: The perimeter of a rectangles is the sum of twice the length and twice the width
Words: The perimeter of a triangle is the sum of the measures of all three sides.
Symbols: P= 2l + 2w or 2(l + w)
Symbols: P = a + b + c l b w w a l c

4. Example 1. Find the perimeter of the triangle. P = a + b + c 28.5 cm

5. Example
2. Find the perimeter of a rectangle with length 15.2 meters and width 10.5 meters.

6. Find the Length
3. The perimeter of a rectangle is 42 feet. Its width is 10 feet. Find the length.
P= 2l + 2w

7. Example
4. The perimeter of a rectangle is 26 yards. Its length is 8 yards. Find the width.

8. Rectangle Key Concept: Area Words
The area of a rectangle is the product of the length and width
Model
Symbols
A = lw w
Symbols
A = lw l

9. Triangle Key Concept: Area Words
The area of a triangle is one-half the product of the base and height
Model
Symbols
A = 1/2bh h b

10. Example

11. On your Own
1. The perimeter of a rectangle is 45 meters. Its width is 6 meters. What is the length of the rectangle?

12. On your Own
2. Dena’s mother is making a rectangular quilt. She has 117 squares and wants the quilt to be nine squares wide. How many squares will make up the length of the quilt?

13. H.O.T. Problem
1. Classify the following statements as true or false. Explain your reasoning and provide examples.
A. The area of a larger rectangle that can be divided into smaller rectangles is the sum of the areas of the smaller rectangles.
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14. H.O.T. Problem
B. The area of a larger rectangle that can be divided into smaller rectangles is the sum of the perimeters of the smaller rectangles.
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15. Writing in Math
Describe the effect on the perimeter and area of a rectangle if its length and width are doubled.
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