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Mon 22 Aug, 2005 04:10 pm
A cylindrical post has a cross section that is a circle with a radius of 3 inches. A piece of cord can be wound around it exactly 7 times.
How long is the piece of cord? Use 22/7 as the value of PI.
My work:
A = 22/7 (3^2) (7)
A = 198
However, the correct answer is 132. How can I find the right answer?
Why are you using A = pi r^2.?
In this formula A is the area of a circle. How does the area have anything to do with the length of a cord?
I think you need to find another equation.
When doing these problems, make sure you understand the equations you are using and can use them in the right circumstances.
ok
Can you show me the steps or atleast disclose the correct formula?
I would be able to take it from there.
What do you find by winding a cord around the outside of a circle (Hint: it's not the area)?
ok
Are you talking about the circumference?
C = PId
C = 22/7 (6) (7 times around) = 132.
Got it.
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