Circles, sectors and arcs

Question 1

What is the radius of a circle?

Answer 1

The distance from the edge of the circle to the centre.

Question 2

What is the diameter of a circle?

Answer 2

Double the radius.

Question 3

What is the circumference of a circle?

Answer 3

It is another word for the perimeter of a circle. It is calculated by multiplying π by the diameter. π is an irrational number representing the ratio between the diameter and the circumference.

Question 4

How do you find the area of a circle?

Answer 4

By squaring the radius and then multiplying it by π.

Question 5

What is a chord?

Answer 5

A straight line joining two points on the circumference.

Question 6

What is an arc?

Answer 6

Part of the circumference of a circle.

Question 7

What is a segment?

Answer 7

An area enclosed by a chord and an arc.

Question 8

What is a sector?

Answer 8

An area enclosed by two radii and an arc.

Question 9

What is a tangent?

Answer 9

A straight line that touches the edge of a circle once.

Question 10

How do you find the length of an arc?

Answer 10

You find a what fraction of a full turn the arc is. You then multiply it by π and the diameter.

Question 11

How do you find the area of a sector?

Answer 11

You find what fraction of a full turn the sector is. You then multiply this by π and the radius squared.