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by gmatmachoman » Sat May 29, 2010 10:01 pm
My approach :
Length of arc ABC : 24

Arc AB +Arc BC = Arc ABC

Since it is a equilateral triangle, arc should be of equal length.

Arc AB = 12

Arc BC=12

Arc CA= 12

So Perimeter/circumference = Total Arc Length = Arc AB+Arc BC+Arc CA
= 12+12+12
= 36

Pi *d = 36

d= 11.45 equivalent to 11

Pick C
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by selango » Sun May 30, 2010 2:04 am
Another approach,

Since abc is equilateral,all angles are equal and 60.

Let the centre of triangle be O.

-->AOB=120 and BOC=120

Length of arc ABC=Length of arc AB+Length BC

24=120/360*pi*d+120/360*pi*d

pi*d=36

-->11 approx
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by gmatjedi » Sun May 30, 2010 4:07 am
24=240/360 * 2*pi * r

r=18/pi

d=36/pi

=11
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