Inaugurated by IN-SPACe
ISRO Registered Space Tutor
S3-SA2-0404
What is the Perimeter of a Rectangle?
Grade Level:
Class 6
AI/ML, Data Science, Physics, Economics, Cryptography, Computer Science, Engineering
Definition
What is it?
The perimeter of a rectangle is the total distance around its outer edge. Imagine walking along all four sides of a rectangular field; the total distance you walk is its perimeter.
Simple Example
Quick Example
Imagine your mobile phone screen. It's a rectangle. If the length is 15 cm and the width is 7 cm, the perimeter is the total distance if you trace all four sides: 15 cm + 7 cm + 15 cm + 7 cm = 44 cm.
Worked Example
Step-by-Step
Let's find the perimeter of a rectangular school playground that is 50 meters long and 30 meters wide.
1. Identify the given values: Length (L) = 50 meters, Width (W) = 30 meters.
---
2. Recall the formula for the perimeter of a rectangle: Perimeter = 2 * (Length + Width).
---
3. Substitute the values into the formula: Perimeter = 2 * (50 meters + 30 meters).
---
4. First, add the length and width: 50 + 30 = 80 meters.
---
5. Now, multiply the sum by 2: Perimeter = 2 * 80 meters.
---
6. Calculate the final value: Perimeter = 160 meters.
---
ANSWER: The perimeter of the school playground is 160 meters.
Why It Matters
Understanding perimeter helps engineers design buildings, architects plan room sizes, and even city planners lay out roads. It's a fundamental concept used in fields like computer graphics for drawing shapes and in robotics for path planning, helping build the apps and tech you use every day.
Common Mistakes
MISTAKE: Adding only the length and width | CORRECTION: Remember to add all four sides, or use the formula P = 2 * (L + W) which accounts for all four sides.
MISTAKE: Confusing perimeter with area | CORRECTION: Perimeter is the distance around the boundary, while area is the space inside the boundary. They are different concepts.
MISTAKE: Forgetting the units in the final answer | CORRECTION: Always write the correct unit (like cm, m, km) with your perimeter value.
Practice Questions
Try It Yourself
QUESTION: A rectangular photo frame has a length of 20 cm and a width of 10 cm. What is its perimeter? | ANSWER: 60 cm
QUESTION: Your dad wants to put a decorative border around a rectangular rug that is 3 meters long and 1.5 meters wide. How much border material does he need? | ANSWER: 9 meters
QUESTION: A rectangular garden has a perimeter of 100 meters. If its length is 30 meters, what is its width? | ANSWER: 20 meters
MCQ
Quick Quiz
What is the perimeter of a rectangle with a length of 8 cm and a width of 4 cm?
12 cm
32 cm
24 cm
16 cm
The Correct Answer Is:
C
The perimeter is 2 * (Length + Width) = 2 * (8 + 4) = 2 * 12 = 24 cm. Options A and D are incorrect as they don't use all sides, and B is the area.
Real World Connection
In the Real World
When a tailor stitches a border around a rectangular saree or a carpenter frames a rectangular window, they need to calculate the perimeter to know how much material to buy. Even in sports, like marking the boundary of a cricket field, understanding perimeter is crucial for accurate measurements.
Key Vocabulary
Key Terms
PERIMETER: The total distance around the outside of a shape | RECTANGLE: A four-sided shape with opposite sides equal and all angles 90 degrees | LENGTH: The longer side of a rectangle | WIDTH: The shorter side of a rectangle | FORMULA: A mathematical rule or equation
What's Next
What to Learn Next
Great job understanding perimeter! Next, you can learn about the 'Area of a Rectangle'. Area tells you the space inside a shape, which is another important measurement often used with perimeter in real-life situations.
