GmatPrep: Geometry
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How to solve this? Also can anybody tell me the difficulty level of this question?
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- Master | Next Rank: 500 Posts
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I could be wrong, but I think that this problem is around the 600 level.
First thing that you need to do is find the circumference of the circle. An equilateral triange divides the circumference into 3 equal parts.
ABC (which is 2/3 of circumference) = 24
So C*(2/3) = 24
C = 36
Now use the formula C = Pie(d)
36 = Pie*D
D = 36/Pie
D = approximately 11
Note: you do not have to find the exact answer, since pie = 3.14..., divide 36 by 3 = 12, then realize that since pie is a little more than 3, the answer will be approximately 11.
Other things good to know:
square root of 2 = approx. 1.4
square root of 3 = approx. 1.7
First thing that you need to do is find the circumference of the circle. An equilateral triange divides the circumference into 3 equal parts.
ABC (which is 2/3 of circumference) = 24
So C*(2/3) = 24
C = 36
Now use the formula C = Pie(d)
36 = Pie*D
D = 36/Pie
D = approximately 11
Note: you do not have to find the exact answer, since pie = 3.14..., divide 36 by 3 = 12, then realize that since pie is a little more than 3, the answer will be approximately 11.
Other things good to know:
square root of 2 = approx. 1.4
square root of 3 = approx. 1.7
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- Master | Next Rank: 500 Posts
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mike22629 wrote:I could be wrong, but I think that this problem is around the 600 level.
First thing that you need to do is find the circumference of the circle. An equilateral triange divides the circumference into 3 equal parts.
ABC (which is 2/3 of circumference) = 24
So C*(2/3) = 24
C = 36
Now use the formula C = Pie(d)
36 = Pie*D
D = 36/Pie
D = approximately 11
Note: you do not have to find the exact answer, since pie = 3.14..., divide 36 by 3 = 12, then realize that since pie is a little more than 3, the answer will be approximately 11.
Other things good to know:
square root of 2 = approx. 1.4
square root of 3 = approx. 1.7
I solved this problem a little differently.
AB + BC + AC = 2pi(r)
If you look at arc AB= the central angle is 120 degrees
therefore (2 pi r)- 120/360 (2 pi r) -120/360 (2 pi r)
will give us
2 pi r - (4/3 pi r)
however we know that 4/3 pi r = 24
therefore we can find r is approx 6.
the closest answer is 11