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Circles

Circles. How do you find the circumference, radius, and diameter of a circle?. What is a circle?. A circle is a plane figure that is curved. Circles do NOT have sides or angles. Where do you see circles in our classroom?. Write these down in your math notebook. What is circumference?.

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Circles

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  1. Circles How do you find the circumference, radius, and diameter of a circle?

  2. What is a circle? • A circle is a plane figure that is curved. • Circles do NOT have sides or angles.

  3. Where do you see circles in our classroom? Write these down in your math notebook.

  4. What is circumference? • Circumference is the distance around a circle. • How can you find the circumference of your Oreo cookie using a piece of yarn and a ruler?

  5. What is the diameter of a circle? • The diameter of a circle is the distance across a circle. • If you walked from one side of a circle to the other side, you would be walking the diameter of the circle. • Can you find the diameter of your Oreo cookie? diameter

  6. What is the radius of a circle? • The radius of a circle is half of the diameter. • If you walked halfway across a circle, you would be walking the radius of the circle. • Can you find the radius of your Oreo cookie? radius

  7. How do you find the radius of a circle if you know the diameter? • You can find the radius of a circle if you know the diameter of the circle by dividing the diameter in half. • Can anyone think of an easy way to divide a number in half? Is there a number we use to divide other numbers in half?

  8. Can you find the radius of this circle? You know that the diameter is 10cm. You can divide 10cm in half to find the radius. 10cm ÷ 2 = 5cm Find the Radius Diameter = 10cm

  9. Do you know the diameter of the circle? How can you find the radius? What operation should you use? Try It Out!!! diameter= 12cm

  10. Is this how you solved the problem? • You can find the radius of this circle by dividing the diameter in half, or by 2. • 12cm ÷ 2= 6cm • The radius of the circle is 6cm.

  11. If the radius is given, you can double the radius to find the diameter. Find the diameter of this circle by doubling the radius that is given. 4cm x 2= 8cm The diameter of this circle is 8cm. How can the diameter be found if the radius is given? radius= 4cm

  12. Do you know the diameter of the circle? How can you find the diameter? Which operation should you use? Try This Out!!! radius= 6in.

  13. Is this how you solved the problem? • You can find the diameter of the circle by adding the radius two times or by multiplying the radius by 2. 6cm + 6cm= 12cm Or 6cm x 2= 12cm

  14. Find the radius of each circle using the diameter that is given. 1. Diameter= 24cm Diameter= 18in. Diameter= 36mm Diameter = 14in. Find the diameter of each circle using the radius that is given. Radius= 7in. Radius= 9cm Radius= 23mm Radius= 52cm Practice

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