 # Find Circumferences of Circles Using Their Radii (2)

In this worksheet, students use formulae to calculate the circumferences of circles given their radii. Key stage:  KS 2

Curriculum topic:   Maths and Numerical Reasoning

Curriculum subtopic:   2D Shapes: Circles, Angles and Bearings

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### QUESTION 1 of 10

This worksheet is about finding the circumferences of circles.

The circumference of a circle is its perimeter or the distance around its edge.

You must learn these two important formulae for a circle of radius, r or diameter, d:

Circumference of a circle = 2πr

Circumference of a circle = πd  Example 1

Find the circumference of a circle of radius 6 cm.

Circumference = 2 × π × r = 2 × π × 6 = 12 × π = 37.7 cm  (1 dp)

Example 2

Find the circumference of a circle of diameter 6 cm.

Circumference = π × d = π × 6 = 18.8 cm  (1 dp)

Find the circumference of a circle of diameter 15.5 cm.

(Just write the number to 1 decimal place)

Find the circumference of a circle of radius 12 cm.

(Just write the number to 1 decimal place)

Find the circumference of a circle of diameter 5.8 cm.

(Just write the number to 1 decimal place)

Find the circumference of a circle of radius 2.5 cm.

(Just write the number to 1 decimal place)

Find the circumference of a circle of radius 5.99 cm.

(Just write the number to 1 decimal place)

Find the circumference of a circle of diameter 4.5 cm.

(Just write the number to 1 decimal place)

Find the circumference of a circle of diameter 15.9 cm.

(Just write the number to 1 decimal place)

Find the circumference of a circle of radius 35 cm.

(Just write the number to 1 decimal place)

Find the circumference of a circle of radius 0.7 cm.

(Just write the number to 1 decimal place)

Find the circumference of a circle of radius 11.1 cm.

(Just write the number to 1 decimal place)

• Question 1

Find the circumference of a circle of diameter 15.5 cm.

(Just write the number to 1 decimal place)

48.7
EDDIE SAYS
π × 15.5
• Question 2

Find the circumference of a circle of radius 12 cm.

(Just write the number to 1 decimal place)

75.4
EDDIE SAYS
2 × π × 12
• Question 3

Find the circumference of a circle of diameter 5.8 cm.

(Just write the number to 1 decimal place)

18.2
EDDIE SAYS
π × 5.8
• Question 4

Find the circumference of a circle of radius 2.5 cm.

(Just write the number to 1 decimal place)

15.7
EDDIE SAYS
2 × π × 2.5
• Question 5

Find the circumference of a circle of radius 5.99 cm.

(Just write the number to 1 decimal place)

37.6
EDDIE SAYS
2 × π × 5.99
• Question 6

Find the circumference of a circle of diameter 4.5 cm.

(Just write the number to 1 decimal place)

14.1
EDDIE SAYS
π × 4.5
• Question 7

Find the circumference of a circle of diameter 15.9 cm.

(Just write the number to 1 decimal place)

50.0
EDDIE SAYS
π × 15.9
• Question 8

Find the circumference of a circle of radius 35 cm.

(Just write the number to 1 decimal place)

219.9
EDDIE SAYS
2 × π × 35
• Question 9

Find the circumference of a circle of radius 0.7 cm.

(Just write the number to 1 decimal place)

4.4
EDDIE SAYS
2 × π × 0.7
• Question 10

Find the circumference of a circle of radius 11.1 cm.

(Just write the number to 1 decimal place)

69.7
EDDIE SAYS
2 × π × 11.1
---- OR ----

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