Welcome to the second of our Medium level Eleven Plus maths quizzes on shapes. In the last one we tested you on triangles. In this one, we will ask you some questions on the properties of circles.

Circles are one of the most common shapes you will encounter – both in maths lessons and in real life. They are not like polygons, such as squares or triangles. Circles have their own terms and their own formulae for working out things like circumference, area, diameter and more!

One thing you need to know is π. This is the Greek letter pi, pronounced the same as Pie.

If you can get all ten questions right in this quiz, well done! You certainly know your circles. Why not try the rest of our quizzes on shapes? Keep playing them until you can get every answer in every quiz right first time. If you can do that then your knowledge of shapes is most definitely in shape!

1.

What is the formula to calculate the circumference of a circle?

Π x radius

Π x diameter

Π x radius^{2}

Π x diameter^{2}

There are several formulae we use that involve π and you would do well to learn them!

2.

What do we call a line which joins two points on the edge of a circle but does not pass through its centre?

Diameter

Sector

Chord

Arc

When a chord passes through the centre of a circle it is called its diameter

3.

What is the value of π to four decimal places?

3.1425

3.1415

3.1416

3.1419

Π goes on forever! Here it is to 100 decimal places: 3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679

4.

What is the name of a shape that forms half a circle?

A moon

A hemi-circle

A demi-circle

A semi-circle

Hemi, demi and semi all mean half, but a half-circle is a semi-circle. Half a sphere is called a hemi-sphere. A half-moon shape is a semi-circle, but most of the time the moon is shaped like a crescent

5.

Which one of the following statements is incorrect?

All the points on the edge of a circle are the same distance from its centre

A tangent is a straight line that touches a single point on the edge of a circle

All the points on the edge of a circle are the same distance from one another

A sector is the part of a circle between two radii (plural of radius) and its edge

All the points on the edge of a circle are the same distance from its centre – that’s how pairs of compasses are able to draw circles

6.

Which one of the following statements is incorrect?

An oval shape is known as an ellipse

A circle has the shortest perimeter (circumference) possible for a shape with the same area

A circle has infinite lines of symmetry

A circle has a longer perimeter (circumference) than a square with the same area

Ellipses are like “squashed” circles – the planets orbit the sun in ellipses.

Circles are the most symmetrical of all shapes, and they have the shortest possible perimeter for any given area

Circles are the most symmetrical of all shapes, and they have the shortest possible perimeter for any given area

7.

Which one of the following statements is incorrect?

The distance around the outside of a circle is called the perimeter

A circle is a round, 2-D shape that looks like a letter ‘O’

A straight line from the centre of a circle to its edge is called the radius

The distance around the outside of a circle is called the circumference

I hope that you didn't get this wrong! The perimeter of a curved shape or arc is known as the circumference

8.

What does the following formula tell us about a circle?

Πr^{2}

Πr

Its circumference

Its area

Its diameter

Its volume

Area is always measured in units squared (e.g. cm^{2})

9.

Which one of the following statements is correct?

The full arc of a circle measures 90^{o}

The full arc of a circle measures 180^{o}

The full arc of a circle measures 270^{o}

The full arc of a circle measures 360^{o}

There are 360^{o} in a full circle. A semi-circle has 180^{o}, a quarter-circle 90^{o}, and a three-quarter circle has 270^{o}

10.

We use a Greek letter π to help us work formulae for circles. What is its name?

Pi

Alpha

Phi

Gamma

Pi or π is an important number where circles are concerned. Try to remember its value if you can: 3.142