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Find Circumferences and Areas of Circles Using a Calculator

In this worksheet, students find the circumferences and areas of circles given their radii. They use a calculator to work out their answers.

'Find Circumferences and Areas of Circles Using a Calculator' worksheet

Key stage:  KS 3

Curriculum topic:   Number

Curriculum subtopic:   Use Calculators/Technology for Accuracy

Difficulty level:  

Worksheet Overview

QUESTION 1 of 10

This worksheet is about finding the circumferences and areas of circles using a calculator.

 

You must learn the two important formulae below to find the radius of a circle (r)

 

Circumference of a circle = 2 π r

Area of a circle = π r2

 

Examples

Find the circumference and area of a circle of radius 6 cm.

 

Answers

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

Area = π r2 =  π x 62 = π x 36 = 113.1 cm2  (1 dp)

Find the circumference of a circle of radius 25 cm.

 

(Give your answer to 1 decimal place)

Find the circumference of a circle of radius 26 cm.

 

(Give your answer to 1 decimal place)

Find the circumference of a circle of radius 71 cm.

 

(Just write the number to 1 decimal place)

Find the circumference of a circle of radius 16 cm.

 

(Just write the number to 1 decimal place)

Find the circumference of a circle of radius 57 cm.

 

(Just write the number to 1 decimal place)

Find the area of a circle of radius 41 cm.

 

(Just write the number to the nearest whole number)

Find the area of a circle of radius 31 cm.

 

(Just write the number to the nearest whole number)

Find the area of a circle of radius 4 cm.

 

(Just write the number to the nearest whole number)

Find the area of a circle of radius 43 cm.

 

(Just write the number to the nearest whole number)

Find the area of a circle of radius 13 cm.

 

(Just write the number to the nearest whole number)

  • Question 1

Find the circumference of a circle of radius 25 cm.

 

(Give your answer to 1 decimal place)

CORRECT ANSWER
157.1
EDDIE SAYS
To calculate the radius we know that our calculation is 2 x π x r 2 x π x 25 = 157.07963.. To one decimal place this becomes 157.1- always check what decimal place the question asks you to give.
  • Question 2

Find the circumference of a circle of radius 26 cm.

 

(Give your answer to 1 decimal place)

CORRECT ANSWER
163.4
EDDIE SAYS
2 x π x 26 = 163.362817... To one decimal place, this gives us 163.4
  • Question 3

Find the circumference of a circle of radius 71 cm.

 

(Just write the number to 1 decimal place)

CORRECT ANSWER
446.1
  • Question 4

Find the circumference of a circle of radius 16 cm.

 

(Just write the number to 1 decimal place)

CORRECT ANSWER
100.5
  • Question 5

Find the circumference of a circle of radius 57 cm.

 

(Just write the number to 1 decimal place)

CORRECT ANSWER
358.1
  • Question 6

Find the area of a circle of radius 41 cm.

 

(Just write the number to the nearest whole number)

CORRECT ANSWER
5281
EDDIE SAYS
Area = π x r² π x 41² = 5281.0172... To the nearest whole number, we would write 5281. Don't worry if you got caught out and gave your answer to one decimal point instead- this is how you learn!
  • Question 7

Find the area of a circle of radius 31 cm.

 

(Just write the number to the nearest whole number)

CORRECT ANSWER
3019
EDDIE SAYS
We know that area = π x r² π x 31² = 3019.070... Be careful, this question asks that we give our number to the nearest whole number. So, we needed to write 3019.
  • Question 8

Find the area of a circle of radius 4 cm.

 

(Just write the number to the nearest whole number)

CORRECT ANSWER
50
  • Question 9

Find the area of a circle of radius 43 cm.

 

(Just write the number to the nearest whole number)

CORRECT ANSWER
5809
  • Question 10

Find the area of a circle of radius 13 cm.

 

(Just write the number to the nearest whole number)

CORRECT ANSWER
531
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