CIRCUMFERENCE
Definition Of Circumference
The complete distance around a circle or a closed curve is called its Circumference.
More About Circumference
The formula for the circumference of a circle, C = 2 × π × r = π × d, where `r` is the radius and `d` is the diameter of the circle.π =22/7 = 3.141.
Another name for circumference is perimeter.
Video Examples: Circumference of a Circle
Example of Circumference
The circumference of the given circle is shown in red.
Solved Example onCircumference
Ques: Find the circumference of the circle.
Choices:
A. 8 cm
B. 88 cm
C. 4 cm
D. 44 cm
Correct Answer: B
Solution:
Step 1: The distance around the circle is called its circumference.
Step 2: Circumference of a circle = 2πr, where r is the radius of the circle and π = 22/7.
Step 3: Radius = r = 14 cm [From the figure.]
Step 4: Circumference = 2 × 22/7 × 14 [Substitute 14 for radius and 22/7 for π.]
Step 5: = 2 × 22 × 2
Step 6: = 88 [Multiply.]
Step 7: The circumference of the circle is 88 cm.
Quick Summary
- Circumference is the distance around a circle.
- It can be calculated using the formula C = 2πr or C = πd, where r is the radius and d is the diameter.
- π (pi) is approximately equal to 3.141 or 22/7.
🍎 Teacher Insights
Use real-world examples like pizza or circular objects to illustrate the concept. Hands-on activities with measuring circular objects can reinforce understanding.🎓 Prerequisites
- Basic understanding of circles
- Concept of radius and diameter
- Multiplication and division
Check Your Knowledge
Q1: A circle has a radius of 7 cm. What is its circumference?
Q2: The diameter of a circle is 10 cm. What is the circumference?
Frequently Asked Questions
Q: What is the relationship between circumference and diameter?
A: The circumference of a circle is π (pi) times its diameter.
Q: How do you find the circumference if you only know the radius?
A: Multiply the radius by 2 and then by π (pi).