Area Of Circles

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Area Of Circles

  1. 1. Area of Circles<br />Today you will learn to find the area of circles.<br />
  2. 2. Review<br />diameter (d)<br />radius (r)<br />d=2r<br />
  3. 3. Area of Circles<br /> The area of a circle is equal to the product of pi () and the square of it’s radius. <br />A=r2<br />
  4. 4. Area of Circles<br />Find the area of the circle below.<br />A=r2<br /> A≈ 3.14(3)2<br />A≈ 3.14(9)<br /> A≈ 28.26 m2<br />3 m<br />
  5. 5. Area of Circles<br /> Your turn:<br />Find the area of a circle with <br />radius 10 cm.<br />Remember to show all of your work!<br />
  6. 6. Area of Circles<br />A=r2<br /> A≈ 3.14(10)2<br /> A≈ 3.14(100)<br /> A≈ 314 cm2<br />
  7. 7. Area of Circles<br />Find the area of a circle with a diameter of 10 m.<br />A=r2<br />You must find the radius before you can find the area!<br />
  8. 8. Area of Circles<br />Find the radius by dividing the diameter by 2.<br /> d=10 m <br />r=d÷2<br /> r=10÷2<br />r= 5 m<br />
  9. 9. Area of Circles<br />Now that you have found the radius of the circle, you can find the area.<br /> A=r2<br /> A ≈ 3.14(5)2<br /> A ≈ 3.14(25)<br /> A ≈ 78.5 m2<br />
  10. 10. Area of Circles<br /> Now it’s your turn to try one!<br /> Find the area of a circle with diameter 40 mm.<br />
  11. 11. Area of Circles<br /> A=r2<br />A ≈ 3.14(20)2<br /> A ≈ 3.14(400)<br /> A ≈ 1256 mm2<br />
  12. 12. Area of Circles<br />Homework: Practice Workbook<br /> Lesson 11-6<br />Don’t forget to show all of your work!<br />

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