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ErinWeeks

  • one year ago

Find the surface area of the cone to the nearest tenth.

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  1. ErinWeeks
    • one year ago
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  2. ErinWeeks
    • one year ago
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    A. 203 cm2 B. 1341.5 cm2 C. 747.7 cm2 D. 213.5 cm2

  3. phi
    • one year ago
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    here is the formula http://math.about.com/od/formulas/ss/surfaceareavol_2.htm

  4. phi
    • one year ago
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    can you match your numbers to the variable names in the formula?

  5. ErinWeeks
    • one year ago
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    i got 441 pi but thats not right..

  6. ErinWeeks
    • one year ago
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    i did 1/3 pi 7^2 27 .. what did i do wrong?

  7. ErinWeeks
    • one year ago
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    ooops i did the volume formula thats why!

  8. ErinWeeks
    • one year ago
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    this time i got 238 thats still not right ...

  9. phi
    • one year ago
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    \[ area = \pi r^2 + \pi r s\] r is 7 and s is 27 is that what you started with ?

  10. phi
    • one year ago
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    it looks like you did not multiply by pi

  11. ErinWeeks
    • one year ago
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    im still getting 238 -_-

  12. ErinWeeks
    • one year ago
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    i did pi*7^2 + pi 7 * 27

  13. phi
    • one year ago
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    238 is r^2 + r*s the formula is pi r^2 + pi*r*s or pi*(r^2 + r*s)

  14. phi
    • one year ago
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    7*7 is 49 7*27 is 189 add together you get 238 no pi

  15. phi
    • one year ago
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    can you figure out how to do it?

  16. ErinWeeks
    • one year ago
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    okay i get that

  17. ErinWeeks
    • one year ago
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    for pi * 7^2 i got 153.86

  18. ErinWeeks
    • one year ago
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    for pi * 7 * 27 i got 593.46

  19. ErinWeeks
    • one year ago
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    so would it be C ???

  20. phi
    • one year ago
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    yes, I thought you figured it out already.

  21. ErinWeeks
    • one year ago
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    okay so it is C?

  22. phi
    • one year ago
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    btw, you should not round to only 2 decimals, because your answer is slightly off. if you used all the digits the calculator gives you you get 747.6990516 which rounds to 747.7

  23. ErinWeeks
    • one year ago
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    okay thank you so much for your help!!!

  24. phi
    • one year ago
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    yw

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