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Radius and circle

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by DavoodBeater » Sun Jan 04, 2009 1:21 pm
pi*r^2 for circular
for square:
40 - 2*pi*r = perimeter of square (note that 2*pi*r = circumference of the circular)
((perimeter of square)/4)^2 = area of square
=> answer is the sum of these two (E)
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by vivek.kapoor83 » Sun Jan 04, 2009 10:46 pm
r - radius of sq
length of wire left after circle cut over = 40-2pi*r

So, from left wire , we made a sq. SO perimeter of sq with side a

4a = 40 -2pi *r
a = (10- (pi*r/2))
sq this u ll find area of sq and area of circle u already know
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by DanaJ » Mon Jan 05, 2009 4:29 am
this one is discussed in "3 Problems from the GMAT Prep Program"
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by shom » Thu Jan 15, 2009 4:48 pm
Thanks for you explanations, but Im still not clear on this.

Can someone try to make it a little easier to understand?
Is there a link to another thread with more explanation that someone can share please?
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by Vemuri » Fri Jan 16, 2009 5:53 am
Its simple. You need to know some formulae here:

Perimeter of a Circle (given radius r) is: 2*pi*r
Area of a circle is: pi*r^2

Perimeter of a square is: 4*length of side
Area of a square is: side^2

Based on the inputs from the question, we know that 'r' is the radius of the circle. So, the perimeter of the circle (length of wire used) is: 2*pi*r

So, the remaining wire is: (40-2*pi*r) that will be used for making a square. The side of the square (40-2*pi*r)/4 (since a square has 4 sides). So, the area of the square will be ((40-2*pi*r)/4)^2. This can be further reduced to (10-pi*r/2)^2

Adding both the areas will give you the answer: pi*r^2 + (10-pi*r/2)^2
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