This document provides information and examples for calculating the circumference of circles. It defines key terms like circumference, diameter, radius, and pi. It derives the formulas for circumference (C = πd and C = 2πr) and provides examples of using the formulas to calculate the circumference of circles with given diameters or radii. At the end, it provides practice problems for finding the circumference of circles using the value of pi as 3.14.

2. GIVE A SENTENCE ON
WHAT YOU CAN SAY
ABOUT THE PICTURE.
WITH SUBJECT AND
PREDICATE.

3. USING MEASURING
TAPE, EACH GROUP
WILL MEASURE THE
CIRCUMFERENCE
OF THE
CARDBOARD PIZZA.
Motivation:

4. VISUALIZING AND FINDING THE
CIRCUMFERENCE OF A CIRCLE
Prepared by:
Jinky A. Beley
Teacher I

5. FINDING THE
CIRCUMFERENCE OF A
CIRCLE
 Circumference is the distance
around the circle.
 Diameter is a chord that connects
two points on the circle and passes
through the center of the circle.
 Radius is one-half the diameter.
 Circle is the set of all points in a
plane with same distance from a
certain point.
diameter
radius radius

6. Pi (π)
 read as “pie”
 is the ratio of the circumference of a circle to its
diameter.
 𝜋 =
𝐶
𝑑
 is an irrational number (a decimal that is non-
repeating and non-terminating) and it cannot be
expressed as a fraction nor a decimal.
 3.14 and
22
7

7. 𝜋 =
𝐶
𝑑
From this concept, 𝜋 =
𝐶
𝑑
. We will
derive the formula for the
circumference of a circle, and use
the cross product rule:

8. 𝜋
1
=
𝐶
𝑑
𝜋 =
𝐶
𝑑
Where:
𝐶 is the circumference
𝑑 is the diameter
1𝐶
𝐶 = 𝜋𝑑
𝜋𝑑
=
Note: We all know that all
whole number has an
imaginary 1 denominator.

9. FORMULA TO FIND THE CIRCUMFERENCE OF A
CIRCLE
𝐶 = 𝜋𝑑
Where:
𝐶 is the circumference
𝑑 is the diameter
𝜋 is equal to 3.14 or
22
7

10.  Since we know that the measure of the diameter is
twice the radius (d=2r), C=πd is the same as
 C=π2r or C=2πr because multiplication is
commutative.
 Now that we have understood the concepts
involving circumference, we are ready to find the
circumference of any circle.

11. Radius: 3m
Diameter: 6m
Circumference:18.84cm
Solution:
C = πd
C = 3.14 x 6 m
C = 18.84 m
6 m

12. RADIUS: 3M
DIAMETER: 6M
CIRCUMFERENCE:18.84CM
SOLUTION:
C = ΠD
C = 3.14 X 6 M
C = 18.84 M
6 m

13. 6 m 14 ft 25 cm
Radius: 3m Radius: 7ft Radius: 25 cm
Diameter: 6m Diameter: 14ft Diameter: 50 cm
Circumference: 18.84cm Circumference: 43.96 ft Circumference: 157 cm
Solution:
𝐶 = 𝜋𝑑
𝐶 = 3.14 𝑥 6 𝑚
𝐶 = 18.84 𝑚
Solution:
𝐶 = 𝜋𝑑
𝐶 = 3.14 𝑥 14 𝑓𝑡
𝐶 = 43.96 𝑓𝑡
Solution:
𝑑 = 2𝑟
𝑑 = 2(25 𝑐𝑚)
𝑑 = 50 𝑐𝑚
𝐶 = 𝜋𝑑
𝐶 = 3.14 𝑥 50 𝑐𝑚
𝐶 = 157 𝑐𝑚
25 cm
6 m 14 ft

15. 6 m 14 ft 25 cm
Radius: 3m Radius: 7ft Radius: 25 cm
Diameter: 6m Diameter: 14ft Diameter: 50 cm
Circumference: 18.84cm Circumference: 43.96 ft Circumference: 157 cm
Solution:
𝐶 = 𝜋𝑑
𝐶 = 3.14 𝑥 6 𝑚
𝐶 = 18.84 𝑚
Solution:
𝐶 = 𝜋𝑑
𝐶 = 3.14 𝑥 14 𝑓𝑡
𝐶 = 43.96 𝑓𝑡
Solution:
𝑑 = 2𝑟
𝑑 = 2(25 𝑐𝑚)
𝑑 = 50 𝑐𝑚
𝐶 = 𝜋𝑑
𝐶 = 3.14 𝑥 50 𝑐𝑚
𝐶 = 157 𝑐𝑚
25 cm
6 m 14 ft

16. FIND THE CIRCUMFERENCE OF EACH CIRCLE. USE 3.14 FOR
THE VALUE OF 𝝅. (NOTE: CIRCLES NOT DRAWN TO SCALE)
12cm. 5in.
EVALUATION!

17. ASSIGNMENT!
A CIRCULAR POND IS
TO BE SURROUNDED
BY A FENCE. THE
RADIUS OF THE POND
IS 3.2 M. HOW MANY
METERS OF FENCE IS
NEEDED TO ENCLOSE
THE POND?
3.2 meters