## Did you know?

We also have Bitesize study guides covering many subjects at National 4 and National 5 on our Knowledge & Learning BETA website.

Home > Maths I > Measure and Shape > Angles involved with circles

Maths I

Angles involved with circles

Next

# Angles Involved with Circles - some questions

You should be able to answer all of the following questions by looking at the information and diagrams that you have seen in the previous pages:

## Example

In this diagram is a diameter and angle .

What is the size of angle ?

is an angle in a semi-circle

so angle

The three angles in the triangle add up to

so angle

### Now try these questions.

Question

In this diagram is the centre of the circle and is a tangent to the circle.

and .

What is the length of ?

is a tangent and is a radius

so angle

We have a right angled triangle and so we can use Pythagoras:

Question

In this diagram is a diameter of the circle and is long. .

Calculate the size of .

is a diameter so we have an angle in a semi-circle and angle .

We have a right angled triangle and so can use Pythagoras.

is not the hypotenuse so:

(to one decimal place)

Impress your mates - how to remember pi to 8 decimal places:

(Don't worry - you don't need to do this in your exam!)

In order to see this content you need to have both Javascript enabled and Flash installed.

Next

BBC iD