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The Circle

The Circle. Investigation of the Circle. Circumference of a circle. Composite shapes Perimeter. Diameter = Circumference ÷ π. The radius is measured from the centre of the circle to the edge. Circumference. radius. diameter. The diameter is measured from one edge to the other

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The Circle

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  1. The Circle Investigation of the Circle Circumference of a circle Composite shapes Perimeter Diameter = Circumference ÷π

  2. The radius is measured from the centre of the circle to the edge. Circumference radius diameter The diameter is measured from one edge to the other passing through the centre of the circle. Parts of the Circle O O = centre of circle Created by Mr Lafferty

  3. Circle Investigation • Construct a table shown below to enable us • to record our results. Created by Mr Lafferty

  4. O Investigation of the Circle Our Investigation To find a relationship between the diameter and circumference of a given circle. Question ? How can we measure the diameter and circumference Created by Mr Lafferty

  5. O Use a ruler Measuring the Diameter of a circle O The diameter is the largest distance between one side of a circle to the other passing through the centre O. Created by Mr Lafferty

  6. O Flexible tape measure Take a tape measure and put it round the circle Read off the measurement Measuring the Circumference of a circle Created by Mr Lafferty

  7. End point Starting point Measuring the Circumference of a circle Roll along an even surface One complete rotation equals the length of the circumference Be careful to avoid slip! Created by Mr Lafferty

  8. Circle Investigation Created by Mr Lafferty

  9. Circle Investigation • Using your results write down, in your own words, • an approximate relationship between the • circumference and diameter for a given circle. “Circumference approximately equals three and bit diameters” Actual value is 3.14 which we write as π Pronounced “Pi” Created by Mr Lafferty

  10. The Circle Now try TJ3a Ex 1 Q2 Ch10 (page 88) Created by Mr. Lafferty Maths Dept.

  11. Starter Questions 4 Created by Mr. Lafferty Maths Dept.

  12. Circumference Learning Intention Success Criteria • Recall knowledge of circles so far. • 1. We are learning to calculate the circumference (perimeter) of a circle. • 2. Apply knowledge so calculate the circumference for a circle showing appropriate working. Created by Mr. Lafferty Maths Dept.

  13. radius Diameter Circumference Main Parts of a Circle Main parts of the circle O Created by Mr. Lafferty Maths Dept.

  14. Calculating the Circumference Example : Find the length of the circumference (Perimeter) of each circle 2cm 10cm Created by Mr. Lafferty Maths Dept.

  15. The Circle Now try TJ3a Ex 2 Ch10 (page 89) Created by Mr. Lafferty Maths Dept.

  16. Starter Questions Created by Mr. Lafferty Maths Dept.

  17. Perimeter Learning Intention Success Criteria • Recall knowledge of circles so far. • 1. We are learning to calculate the perimeter of composite shapes that including parts of a circle. • 2. Solve mixed problems by applying all our knowledge so far. Created by Mr. Lafferty Maths Dept.

  18. Solution Calculating the Circumference Example Calculate the curved part of this shape. 6m 90o Created by Mr Lafferty

  19. Composite Perimeter ExampleFind the perimeter for the semi-circle shape ? Solution 180o Created by Mr Lafferty

  20. Solution Composite Perimeter ExampleFind the perimeter of the shape below ? 8cm 90o Created by Mr Lafferty

  21. 5 cm 20cm Composite Perimeter Example : Find the perimeter of this shape Perimeter = 3 sides + semicircle Created by Mr. Lafferty Maths Dept.

  22. The Circle Now try TJ3a Ex 3 Ch10 (page 91) Created by Mr. Lafferty Maths Dept.

  23. Starter Questions Created by Mr. Lafferty Maths Dept.

  24. Finding the Diameter The Circle Learning Intention Success Criteria • Understand how to rearrange circumference formula to find diameter. • 1. We are learning to find the diameter of a circle if we know the circumference. • 2. Solve diameter problems. Created by Mr. Lafferty Maths Dept.

  25. Finding the Diameter The Circle We can easily rearrange the circumference formula so that we have the diameter D on one side. You have 1 minute to rearrange equation. Remember change side change sign Created by Mr. Lafferty Maths Dept.

  26. Finding the Diameter The Circle Examples : Find the diameter of each circle given the circumference. C = 62.8 cm C =15.7 cm 5cm 20cm Created by Mr. Lafferty Maths Dept.

  27. Have you updated your Learning Log ? The Circle Now try TJ3a Ex 4 Ch10 (page 93) Created by Mr. Lafferty Maths Dept.

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