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Level 5-6 Shapes - Circles
To the nearest square metre, what is the area of a circular pool with a radius of 10m?

Level 5-6 Shapes - Circles

Circles are everywhere, from wheels to coins. Learn radius, diameter, and π to find circumference and area, then tackle real KS3 problems.

Fascinating Fact:

Coins show perfect circles. A £1 coin with a 23 mm diameter has a circumference of about 72 mm.

In KS3 Maths, you use radius, diameter and π to solve problems about circles. You’ll calculate circumference, area, and work with real measures in contexts like coins, wheels, and maps.

  • Radius: The distance from the centre of a circle to its edge.
  • Diameter: A straight line passing through the centre, touching both sides; it equals twice the radius.
  • Circumference: The distance around a circle; use C = πd or C = 2πr.
How do you find the circumference of a circle in KS3?

Use C = πd if you know the diameter, or C = 2πr if you know the radius. Substitute the value and calculate.

What is the formula for the area of a circle?

The area is A = πr2, where r is the radius. If you have the diameter, halve it to get the radius first.

What value of pi should I use in KS3 Maths?

Use π as 3.14 for most questions, or leave answers in terms of π if instructed (for example, 6π cm).

1 .
What is the area of a circle with a radius of 7 cm (to one decimal place)?
53.9 cm
153.9 cm
315.9 cm
513.9 cm
The radius = 7 cm, so the calculation is: 3.141592 x 7 x 7 = 153.938 cm
2 .
A line which joins the centre of a circle to a point on the circumference is called a .......
centre line
diameter
half distance
radius
It radiates out from the circle's centre
3 .
What can be calculated using πr2?
Area of a circle
Circumference of a circle
Diameter of a circle
Volume of a circle
Remember to use the radius of the circle and not the diameter
4 .
What is the correct formula for the circumference of a circle?
C = 2πr
C = 2πd
C = 2π
C = 3πr
Circumference = 2 x 3.141592 x radius. This formula allows you to make intelligent estimates before you work out the real answer
5 .
The distance measured around a circle is called the .......
brim
circumference
diameter
radius
In circles we call this the circumference rather than the perimeter
6 .
The area of a circular lawn is 628 m2. How far is it across to the nearest metre?
20
24
28
32
Remember, you are asked for the diameter not the radius
7 .
To the nearest square metre, what is the area of a circular pool with a radius of 10 m?
114 m2
214 m2
314 m2
414 m2
The radius = 10 m, so the calculation is: 3.141592 x 10 x 10 = 314.159 m2
8 .
A line which passes through the centre of a circle and joins two points on its circumference is called a .......
centre line
circumference
diameter
radius
The diameter is like 2 radii on the same bearing
9 .
A circular lawn has a 20 m radius. What is the approximate circumference of the lawn?
100 m
126 m
150 m
175 m
Using C = 2 ? r, 2 x 3.141592 x 20, C = 125.66 m
10 .
A round table has a diameter of 200 cm. What is the approximate circumference of the table?
286 cm
628 cm
1,256 cm
I need to know the radius first
Using C = 2 ? r, 2 x 3.141592 x 100, C = 628.3184 cm. Remember to use radius and not diameter!
You can find more about this topic by visiting BBC Bitesize - Circles

Author:  Frank Evans (Specialist 11 Plus Teacher and Tutor)

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