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Back to Unit 4

Lesson 4-1: Area & Perimeter of Rectangles

Scenario: Home Design - Plan your dream room using area and perimeter calculations!

Duration: 50-65 minutesScenario: Home Design

Learning Objectives

  • Calculate area of rectangles using the formula A = length × width
  • Calculate perimeter of rectangles using P = 2(length + width)
  • Solve problems involving composite rectangular shapes
  • Apply area and perimeter concepts to real-world room planning

Room Planning Problem

Bedroom Design

You're designing a rectangular bedroom that is 12 feet long and 10 feet wide. You want to install carpet and baseboards around the room.

Questions:
1. How much carpet do you need? (Area)
2. How much baseboard do you need? (Perimeter)

12 ft
10 ft

Visual representation of the bedroom

Step-by-Step Solution

Step 1: Calculate the area (carpet needed)

Area = length × width
Area = 12 ft × 10 ft = 120 square feet

Step 2: Calculate the perimeter (baseboard needed)

Perimeter = 2(length + width)
Perimeter = 2(12 + 10) = 2(22) = 44 feet

Answer: You need 120 square feet of carpet and 44 feet of baseboard.

Rectangle Formulas

Area Formula

A = l × w

Area = length × width
Units: square units (ft², m², etc.)

Perimeter Formula

P = 2(l + w)

Perimeter = 2 × (length + width)
Units: linear units (ft, m, etc.)

Composite Shapes

L-Shaped Room

An L-shaped room consists of two rectangles: one 8 ft × 6 ft and another 4 ft × 6 ft. Find the total area and perimeter.

Step 1: Calculate area of each rectangle

Rectangle 1: 8 × 6 = 48 ft²
Rectangle 2: 4 × 6 = 24 ft²
Total Area: 48 + 24 = 72 ft²

Step 2: Calculate perimeter (outer edges only)

Outer perimeter: 8 + 6 + 4 + 6 + 4 + 6 = 34 ft

Practice Problems

Problem 1

A rectangular garden is 15 meters long and 8 meters wide. Find the area and perimeter.

Your solution:

Problem 2

A rectangular pool has an area of 200 square feet and a width of 10 feet. What is its length and perimeter?

Your solution: