GMAT Prep - Geometry

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by jawanindia2007 » Mon Jul 14, 2008 10:43 pm
Is the answer to this question B?

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by BlueRain » Mon Jul 14, 2008 10:49 pm
I believe the OA should be A.

I'll explain if it is the right answer :?:

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by jawanindia2007 » Mon Jul 14, 2008 10:51 pm
sorry typo......... ithink it is c.let me know if i am right

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by ksh » Mon Jul 14, 2008 11:09 pm
jawanindia2007 wrote:sorry typo......... ithink it is c.let me know if i am right
here the answer is A.

given the length of one side it can be deduced through the isosceles triangle, the length of required side.

hence A

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by ksh » Mon Jul 14, 2008 11:16 pm
ksh wrote:
jawanindia2007 wrote:sorry typo......... ithink it is c.let me know if i am right
Statemet 1. AD=6
angle ADB=180-2x

So, angleB=x
which means triangle ADB is an isosceles. also, from this AD=BD.
After knowing the length of BD, BC is known as the triangle BDC is also an isosceles.

Hence 1 is sufficient.

stmt2. merely knowing the angle cant let one know side of a triangle. Hence, insufficient


hence A

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Re: GMAT Prep - Geometry

by manju_ej » Thu Jul 17, 2008 1:45 am
Angle BDC (2x)= angle DAB(X)+ angle DBA(X)
ie 2X= sum of the non-adjacent angles(X+X)
So it can be concluded, AD =BD = BC.(Isoceles triangles)
Statement (1) AD=6, sufficient , so BC = 6
Statemet (2) X=36, this info just reiterates the fact AD= BD=BC, but without the length of any one of these sides, length of BC cant be found, so Insufficient.
Answer - A