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anonymous

  • one year ago

MEDAL AND FAN 1 All circles are similar to each other. True False 2 Find the exact area of a circle having the given circumference. 8 A = 4√2 16 64 3 Find the exact area of a circle having the given circumference. 3 A = 2.25 3 9 4 Find the exact circumference of a circle with an area equal to 36 sq. in. 12 18 324

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  1. mathstudent55
    • one year ago
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    1. T

  2. mathstudent55
    • one year ago
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    2. Use the circumference formula to find the radius. Then use the area formula to find the area.

  3. mathstudent55
    • one year ago
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    3. Solve it same way as 2.

  4. mathstudent55
    • one year ago
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    4. Use the area formula to find the radius. Then use the circumference formula to find the circumference.

  5. mathstudent55
    • one year ago
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    If you have questions, just ask.

  6. anonymous
    • one year ago
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    cant remember the area formula for a circle

  7. anonymous
    • one year ago
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    can you work out number 2 for me?

  8. anonymous
    • one year ago
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    @mathstudent55

  9. mathstudent55
    • one year ago
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    Here are the formulas you need. \( \Large C_{circle} = 2 \pi r\) \(\Large A_{circle} = \pi r^2\)

  10. anonymous
    • one year ago
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    |dw:1438148434752:dw|

  11. mathstudent55
    • one year ago
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    2 Find the exact area of a circle having the given circumference. 8 A = 4√2 16 64 If the circumference is 8, we set 8 equal to teh circumference formula and find the radius. \(\large C_{circle} = 2 \pi r\) \(\large 8 = 2 \pi r\) \(\large \dfrac{8}{2 \pi} = \dfrac{2 \pi r}{2 \pi} \) \(\large \dfrac{4}{\pi} = r\)

  12. mathstudent55
    • one year ago
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    You stared it out correct. You need to divide both sides by pi. |dw:1438148608264:dw|

  13. mathstudent55
    • one year ago
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    Ok with the radius?

  14. anonymous
    • one year ago
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    do i need to divide 4 by pi or is that the final radius?

  15. mathstudent55
    • one year ago
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    No. Don't divide. The problem wants an exact area, so we can't divide by pi and give an approximate decimal. We need to keep pi in the radius. Now we find the area.

  16. mathstudent55
    • one year ago
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    \(\large A = \pi r^2\) \(\large A = \pi \times \left( \dfrac{4}{\pi} \right) ^2\) Ok so far with the area?

  17. mathstudent55
    • one year ago
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    |dw:1438148873842:dw|

  18. mathstudent55
    • one year ago
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    |dw:1438148931770:dw|

  19. anonymous
    • one year ago
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    so the answer is \[16\]

  20. anonymous
    • one year ago
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    16 pi

  21. anonymous
    • one year ago
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    thanks

  22. mathstudent55
    • one year ago
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    No. Not 16*pi It's 16/pi

  23. mathstudent55
    • one year ago
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    Wait. There is no pi at all in problem 2 or in the choices. Was the circumference 8 or 8pi?

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