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gabbyalicorn

  • one year ago

What is the exact area of a circle whose diameter is 18 cm?

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  1. jim_thompson5910
    • one year ago
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    formula A = pi*r^2 pi = 3.14 approximately r = radius = half of diameter

  2. gabbyalicorn
    • one year ago
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    |dw:1433387436296:dw|

  3. jim_thompson5910
    • one year ago
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    ok so each answer is in terms of pi, so ignore the pi's for now

  4. gabbyalicorn
    • one year ago
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    whats the radius?

  5. jabez177
    • one year ago
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    18 divided by 2

  6. jim_thompson5910
    • one year ago
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    diameter = 18 radius = half of diameter

  7. gabbyalicorn
    • one year ago
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    so 9

  8. jim_thompson5910
    • one year ago
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    yep

  9. jim_thompson5910
    • one year ago
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    then you plug that into A = pi*r^2

  10. gabbyalicorn
    • one year ago
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    3.14 x 18

  11. jabez177
    • one year ago
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    \[3.14 \times 8 \times 8 \]

  12. gabbyalicorn
    • one year ago
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    200.96

  13. gabbyalicorn
    • one year ago
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    divide it by 2?

  14. jabez177
    • one year ago
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    Wait... Let me try this again...

  15. jim_thompson5910
    • one year ago
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    again, ignore the pi's

  16. jim_thompson5910
    • one year ago
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    every answer choice has a pi in it

  17. gabbyalicorn
    • one year ago
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    8x8 = 64

  18. jim_thompson5910
    • one year ago
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    but you found the radius to be 9, not 8

  19. gabbyalicorn
    • one year ago
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    9 x 8 = 72

  20. jim_thompson5910
    • one year ago
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    r^2 means r times r

  21. jim_thompson5910
    • one year ago
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    r = 9

  22. gabbyalicorn
    • one year ago
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    9 x8 x8 ?

  23. gabbyalicorn
    • one year ago
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    576

  24. jim_thompson5910
    • one year ago
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    idk how you're getting 9 x 8

  25. jim_thompson5910
    • one year ago
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    r^2 = r x r = 9 x 9 = ?? I replaced the 'r's with 9 since the radius is 9

  26. gabbyalicorn
    • one year ago
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    81?

  27. jim_thompson5910
    • one year ago
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    yep so 81pi is your answer

  28. gabbyalicorn
    • one year ago
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    Thank you!!!!

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