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GMAT Prep : DS doubt

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GMAT Prep : DS doubt

by Skywalker » Sun Oct 03, 2010 10:32 am
Hi,

I am able to solve the following sum using either of the 2 options provided & thus feel that the answer ought to be D, but it isnt. the OA [spoiler]= A[/spoiler]. Why ?

Also. am I correct is stating that " the external angle in a triangle is = sum of the 2 opposite internal angles" is the property used while solving for 1st statement ?



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StAy HuNgry sTay fOOlisH
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by narik11 » Sun Oct 03, 2010 10:52 am
Skywalker wrote:Hi,

I am able to solve the following sum using either of the 2 options provided & thus feel that the answer ought to be D, but it isnt. the OA [spoiler]= A[/spoiler]. Why ?

Also. am I correct is stating that " the external angle in a triangle is = sum of the 2 opposite internal angles" is the property used while solving for 1st statement ?



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u have to use the above said property.
So the left triangle will also be isosceles and hence AD=BD
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by diebeatsthegmat » Sun Oct 03, 2010 6:29 pm
Skywalker wrote:Hi,

I am able to solve the following sum using either of the 2 options provided & thus feel that the answer ought to be D, but it isnt. the OA [spoiler]= A[/spoiler]. Why ?

Also. am I correct is stating that " the external angle in a triangle is = sum of the 2 opposite internal angles" is the property used while solving for 1st statement ?



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you are having the same problem as i am having... lol... its just because we dont pay attention or dont focus on the maths...
statement 2 will be sufficient if we know the length of some side, however we dont know anything about the length of any side....thus although we know that BD=AD=BC but we have no length thus no answer
the correct answer is A
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