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In triangle ABC above, what is the lenght of side BC? 1) [#permalink]
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16 Jul 2007, 13:44
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35% (01:48) correct
65% (00:35) wrong based on 38 sessions
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In triangle ABC above, what is the lenght of side BC?
1) line segment AD has lenght 6
2) x=36
OA later explain reasoning
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Where is the figure? Without the figure, it is kind of hard to picture where x is and where point D lies.



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don't you see it?? i ve attached it with the post... ????



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1
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Sorry, I did see it now.
The answer should be A.
We know from the figure that <BAC=x , <BDC=<BCD=2x
So BD=BC, since <BDC=<BAC+<ABD, this tells you <ABD=x as well.
Therefore, AD=BD, since we have already find out that BD=BC, so AD=BC. Statement 1 alone is sufficient.
Statement 2 tells you the value of X, but didn't tell you anything about the length of the segment, therefore is not sufficient.



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Re: Gmat prep triangle lenght of side BC [#permalink]
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23 Oct 2010, 15:12
Awesome Just one simple explanation for how <BDC = <BAC+<ABD, exterior angle in a triangle is the sum of the opposite interior angles. It took me a while to figure it out, may be helpful.



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Re: Gmat prep triangle lenght of side BC [#permalink]
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08 Nov 2010, 06:06
+1 A
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Re: Gmat prep triangle lenght of side BC [#permalink]
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22 Nov 2010, 09:17
I was going to pick A originally, but upon seeing that x=36 (I assumed that x should be 30), I felt no choice but to pick C. Why is it unnecessary to know what x is?
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Re: Gmat prep triangle lenght of side BC [#permalink]
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22 Nov 2010, 13:15
rockzom wrote: I was going to pick A originally, but upon seeing that x=36 (I assumed that x should be 30), I felt no choice but to pick C.
Why is it unnecessary to know what x is? Regardless of the actual value of x, we can show that triangle ADB is an isosceles triangle. Within the bounds of the givens in this problem, changing x will only lead to changes in the length of side AB and DC.



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Re: Gmat prep triangle lenght of side BC [#permalink]
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22 Nov 2010, 13:36
(180 2x) + x + ABD = 180
therefore x= abd
So, AB=BD=BC=6; Answer A is sufficient.
B is not sufficient since merely knowing angles does not reach upon length of AB.
Answer: A




Re: Gmat prep triangle lenght of side BC
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22 Nov 2010, 13:36







