# Circles - Using π - Level 1

## Practise using pi to calculate various circle measurements.

##### Level 1Level 2Level 3Level 4Level 5Level 6Exam-StyleDescriptionHelp

This is level 1; find the circumference given the radius or diameter. Give your answers correct to three significant figures. You can earn a trophy if you get at least 7 correct. The diagrams are not drawn to scale.

 The diameter of this circle is 30cm.Calculate the distance around the circle (circumference).Don't forget to round off your answer to three significant figures. cm Calculate the circumference of this circle if the diameter is 6cm. cm This third circle has a diameter of 8.5cm.Calculate its circumference. cm You should be getting good at finding the circumference of a circle by now.Calculate the circumference of this circle if the diameter is 9cm. cm Calculate the circumference of this circle drawn inside a square with sides of length 6.6cm. cm You are given the radius of this circle, not the diameter. What is its circumference? cm Calculate the circumference of a circle if the radius is 3.9cm. cm Calculate the circumference of a circle if the diameter is 7.3cm. cm Calculate the circumference of circular jar if its radius is 73mm. mm The magic roundabout in Swindon consists of five small traffic islands around one large island.Vehicles can drive clockwise around the small islands and anticlockwise around the large island.If a car drives around every island once and finishes in the same place it starter work out the total distance travelled.Assume the small islands have a radius of 5.9m and the large island has a radius of 17.7m. m
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This is Circles - Using pi level 1. You can also try:
Level 2 Level 3 Level 4 Level 5 Level 6 Composites

## Instructions

Try your best to answer the questions above. Type your answers into the boxes provided leaving no spaces. As you work through the exercise regularly click the "check" button. If you have any wrong answers, do your best to do corrections but if there is anything you don't understand, please ask your teacher for help.

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## Description of Levels

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Level 1 - find the circumference given the radius or diameter.

Level 2 - find the radius or diameter given the circumference.

Level 3 - find the area of a circle given either the radius or diameter.

Level 4 - the areas of circles are given, find either the radius, diameter or circumference.

Level 5 - the radius and angle subtended at the centre of the circle are given, find the length of the arc or area of the sector of the circle.

Level 6 - this level has mixed questions about the circle. Most of these questions will require a multi-part calculation once the situation described in the question has been understood.

Areas of composite shapes requires an ability to calculate the areas of other shapes such as rectangles, triangles and trapezia.

Exam Style questions are in the style of GCSE or IB/A-level exam paper questions and worked solutions are available for Transum subscribers.

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## Help with circle calculations

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Use a calculator for this exercise. All of the calculations you will do involve the number π (pronounced pi) which is roughly equal to 3.141592. You should use the π button on your calculator to get this number into your calculation.

Let r be the radius, d the diameter, C the circumference and A the area of a circle.

C = πd    [i.e., to find the circumference multiply the length of the diameter by pi]

A = πr2    [i.e., to find the area multiply the square of the radius by pi]

For arcs multiply the circumference by the angle subtended at the centre and divide by 360.

For sector area multiply the circle area by the angle subtended at the centre and divide by 360.

For help using a calculator with circle calculations see Calculator Workout.

For more on this topic see our Circles page.

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