KS3 Maths Quiz
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 one of the most common shapes. If you think about it, circles are just about everywhere - wheels, gears, pulleys - without circles transport and machinery would be almost impossible. So, with circles being so important, it won't surprise you to learn that they are one of the things you need to know about in KS3 Maths.

There are some special terms relating to circles which you will hopefully be familiar with - radius, diameter, circumference, arc, sector and of course π. In any circle the ratio of the distance around the curved perimeter to the distance across the circle through the centre is represented by π (the Greek letter pi) which has a value of just over 3 (3.1415926535.....)

It's a very good idea to get to know circles, their parts and the formulae associated with them. To help you, try this quiz all about circles. Take your time and read each question carefully before submitting your answers. That way, you won't end up going round and round and round! Good luck!

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1. The distance measured around a circle is called the .......
In circles we call this the circumference rather than the perimeter
2. What is the correct formula for the circumference of a circle?
Circumference = 2 x 3.141592 x radius. This formula allows you to make intelligent estimates before you work out the real answer
3. A round table has a diameter of 200 cm. What is the approximate circumference of the table?
Using C = 2 π r, 2 x 3.141592 x 100, C = 628.3184 cm. Remember to use radius and not diameter!
4. A line which passes through the centre of a circle and joins two points on its circumference is called a .......
The diameter is like 2 radii on the same bearing
5. What is the area of a circle with a radius of 7 cm (to one decimal place)?
The radius = 7 cm, so the calculation is: 3.141592 x 7 x 7 = 153.938 cm
6. What can be calculated using πr2?
Remember to use the radius of the circle and not the diameter
7. The area of a circular lawn is 628 m2. How far is it across to the nearest metre?
8. To the nearest square metre, what is the area of a circular pool with a radius of 10 m?
The radius = 10 m, so the calculation is: 3.141592 x 10 x 10 = 314.159 m2
9. A line which joins the centre of a circle to a point on the circumference is called a .......
It radiates out from the circle's centre
10. A circular lawn has a 20 m radius. What is the approximate circumference of the lawn?
Using C = 2 π r, 2 x 3.141592 x 20, C = 125.66 m

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