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705-805 (Hard)|   Geometry|      
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Bunuel
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As shown in the graph above, the circular base of a large oak tree sit 17 Dec 2017, 23:25
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C
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Difficulty:

75% (hard)

Question Stats:

49% (02:20) correct 51% (02:11) wrong based on 123 sessions

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As shown in the graph above, the circular base of a large oak tree sits in a level field and touches two straight sides of a fence at points A and B. Point C shows where the two sides of the fence meet. How far from the center of the tree's base is point B ?

(1) AB = CB
(2) The center of the base is 25 feet from point C.


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C
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As shown in the graph above, the circular base of a large oak tree sit 17 Dec 2017, 23:25
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Bunuel

As shown in the graph above, the circular base of a large oak tree sits in a level field and touches two straight sides of a fence at points A and B. Point C shows where the two sides of the fence meet. How far from the center of the tree's base is point B ?

(1) AB = CB
(2) The center of the base is 25 feet from point C.


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2017-12-18_1023.png
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This is a modified version of the following OG question: https://gmatclub.com/forum/the-circular ... 67645.html
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As shown in the graph above, the circular base of a large oak tree sit 24 Jan 2018, 05:58
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Hi Bunuel

This one is more complicated than the original one from the OG. Would you mind explaining how to solve it please?

Thanks
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As shown in the graph above, the circular base of a large oak tree sit 24 Jan 2018, 06:32
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Bunuel

As shown in the graph above, the circular base of a large oak tree sits in a level field and touches two straight sides of a fence at points A and B. Point C shows where the two sides of the fence meet. How far from the center of the tree's base is point B ?

(1) AB = CB
(2) The center of the base is 25 feet from point C.


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Attachment:
2017-12-18_1023.png
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Hi..
When we make a triangle ABC..
AC =CB... RULE for a point outside joined by tangents. The point is always at same distance from the point at which the tangent meets circumference..

Let's see the statements..
1) AB=CB...
So triangle ABC is equilateral so angle C us 60..
But we do not know the radius or any other info..
2) OC is 25..
Where O is centre of base..
Insufficient

Combined..
Join OCB..
Now angle C is 60, so angle BACK will be half of it that is 30..
So triangle is 30-60-90..sides are in ratio 1:√3:2
In this hypotenuse is 25..
So OB is 25/2
Sufficient..

C

Bunuel, may be statement I was AC=BC or there is a typo in answer.
I may have skipped something as answering while sitting in concert.
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As shown in the graph above, the circular base of a large oak tree sit 24 Jan 2018, 07:23
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Thanks Chetan2u.
That is exactly what I thought that the answer could be C and not E as is currently shown. Okay so I am not totally mad yet. Thanks
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As shown in the graph above, the circular base of a large oak tree sit 24 Jan 2018, 08:07
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Octobre
Hi Bunuel

This one is more complicated than the original one from the OG. Would you mind explaining how to solve it please?

Thanks
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The OA is C. Edited. Thank you both.
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As shown in the graph above, the circular base of a large oak tree sit 27 Dec 2018, 05:37
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Bunuel, chetan2u,
I came across of this question in DS Challenge Set of Gmat Hacks and there the answer is E. Below is explanation.
Explanation: To find the distance of a line from B to the center of the tree’s
base, we would need to create some kind of figure, probably a triangle, that
included that line, and know something useful (like the angle measures) of that
triangle. Statement (1) doesn’t tell us anything relevant to that distance, so
it is insufficient. Statement (2) is also irrelevant— it doesn’t help us find any
measures of the circle, such as the radius, that might help us. Taken together,
the statements are still not enough. We only know the length of one line, and
as we don’t know the distance from C to the edge of the circle, we can’t use
that length to determine the radius of the circle.
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As shown in the graph above, the circular base of a large oak tree sit 27 Dec 2018, 07:59
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nigina93
Bunuel, chetan2u,
I came across of this question in DS Challenge Set of Gmat Hacks and there the answer is E. Below is explanation.
Explanation: To find the distance of a line from B to the center of the tree’s
base, we would need to create some kind of figure, probably a triangle, that
included that line, and know something useful (like the angle measures) of that
triangle. Statement (1) doesn’t tell us anything relevant to that distance, so
it is insufficient. Statement (2) is also irrelevant— it doesn’t help us find any
measures of the circle, such as the radius, that might help us. Taken together,
the statements are still not enough. We only know the length of one line, and
as we don’t know the distance from C to the edge of the circle, we can’t use
that length to determine the radius of the circle.
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Hi..

If the wordings are the same and they give answer as E, then they are wrong.
The answer will be C here as explained above.
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