1. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. The Circle Circumference Diameter = Circumference ÷ π www.mathsrevision.com Area Radius = √(Area ÷ π ) Mixed Problems

2. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. Starter Questions Starter Questions www.mathsrevision.com 6cm 3cm

3. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. www.mathsrevision.com Learning Intention Success Criteria 1.To revise the basics of the circle. Main Parts of a Circle 1.Remember the terms circumference, diameter and radius. 2.Calculate the circumference using formula.

4. Level 4+ Circumference 1-Jul-16Created by Mr. Lafferty Maths Dept. www.mathsrevision.com Main Parts of a Circle Main parts of the circle radius O Diameter

5. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. Circumference 10cm 2cm Example : Find the length of the circumference (Perimeter) of each circle www.mathsrevision.com

6. Level 4+ Friday, 01 July 2016Friday, 01 July 2016Friday, 01 July 2016Friday, 01 July 2016Created by Mr Lafferty 6 Example Find the perimeter for the semi-circle shape ? Solution 180 o Composite Perimeter www.mathsrevision.com

7. Level 4+ Friday, 01 July 2016Friday, 01 July 2016Friday, 01 July 2016Friday, 01 July 2016Created by Mr Lafferty 7 Example Find the perimeter of the shape below ? Solution 8cm 90 o Composite Perimeter www.mathsrevision.com

8. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. Now try TJN4+ Ex11.1 Ch11 (page 73) www.mathsrevision.com Main part of a Circle

9. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. Starter Questions Starter Questions www.mathsrevision.com 4 5 8

10. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. www.mathsrevision.com Learning Intention Success Criteria 1. We are learning to find the diameter of a circle if we know the circumference. Finding the Diameter The Circle 2.Solve diameter type problems. 1.Understand how to rearrange circumference formula to find diameter.

11. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. www.mathsrevision.com We can easily rearrange the circumference formula so that we have the diameter D on one side. Finding the Diameter The Circle You have 1 minute to rearrange equation. Remember change side change sign

12. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. C = 62.8 cm Example : Find the diameter of each circle given the circumference. 2 0 c m C =15.7 cm 5 c m Finding the Diameter The Circle www.mathsrevision.com

13. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. Now try TJN4+ Ex11.2 Ch11 (page 77) www.mathsrevision.com Finding the Diameter The Circle

14. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. Starter Questions Starter Questions www.mathsrevision.com 6 5

15. Level 4+ Friday, 01 July 2016Friday, 01 July 2016Friday, 01 July 2016Friday, 01 July 2016Created by Mr Lafferty 15 2 3 4 1 2 3 4 5 6 7 8 1 5 6 7 8 If we break the circle into equal sectors And lay them out side by side We get very close to a rectangle. www.mathsrevision.com Area of a Circle Demo

16. Level 4+ Friday, 01 July 2016Friday, 01 July 2016Friday, 01 July 2016Friday, 01 July 2016Created by Mr Lafferty 16 1 2 3 4 5 6 7 8 thinner and thinner sectors If we cut the sectors Thinner and thinner then we get closer and closer to a rectangle. Hence we can represent the area of a circle by a rectangle. www.mathsrevision.com Area of a Circle

17. Level 4+ Friday, 01 July 2016Friday, 01 July 2016Friday, 01 July 2016Friday, 01 July 2016Created by Mr Lafferty 17 But the area inside this rectangle is also the area of the circle www.mathsrevision.com Area of a Circle Area = πr 2

18. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. Area of a circle Q.Find the area of the circle ?Solution 4cm www.mathsrevision.com

19. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. Area of a circle Q. The diameter of the circle is 60cm. Find area of the circle?Solution www.mathsrevision.com

20. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. Now try TJN4+ Ex11.3 Ch11 (page 76) www.mathsrevision.com Area of a Circle

21. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. Starter Questions Starter Questions www.mathsrevision.com In pairs How many different ways are there of finding the radius of a circle ?

22. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. www.mathsrevision.com Learning Intention Success Criteria 1. We are learning how to find the radius given the area. Finding the Radius The Circle 2.Solve radius type problems. 1.Understand how to rearrange area formula to find the radius.

23. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. www.mathsrevision.com We can easily rearrange the area formula so that we have the radius R on one side. Finding the Radius The Circle

24. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. Example : Find the radius of the circle given the area. A = 153.94 cm 2 ? cm Finding the Radius The Circle www.mathsrevision.com

25. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. Now try TJN4+ Ex11.4 Ch11 (page 78) www.mathsrevision.com Mixed Problems The Circle

26. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. Starter Questions Starter Questions www.mathsrevision.com 4

27. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. www.mathsrevision.com Learning Intention Success Criteria 1.Recall knowledge of circles. 1. We are learning to solve problems invloving Area and Perimeter. Mixed Problems 2.Solve mixed problems by applying all our knowledge. The Circle

28. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. www.mathsrevision.com Mixed Problems The Circle Example 1 : Find the area of the shape 20cm 5 cm Area = rectangle + semicircle

29. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. Example : Find the perimeter of this shape 20cm 5 cm Perimeter = 3 sides + semicircle Composite Perimeter www.mathsrevision.com

30. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. www.mathsrevision.com Mixed Problems The Circle Example 2 : A circle is contained in a square. Find the grey shaded area below. Area = square - circle 8cm

31. Level 4+ 1-Jul-16Created by Mr. Lafferty Maths Dept. Now try TJN4+ Ex11.5 Ch11 (page 79) www.mathsrevision.com Mixed Problems The Circle