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# DS: Need explanation too

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Intern
Joined: 20 Jul 2008
Posts: 22
Followers: 0

Kudos [?]: 3 [0], given: 0

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22 Aug 2008, 12:16
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SVP
Joined: 30 Apr 2008
Posts: 1887
Location: Oklahoma City
Schools: Hard Knocks
Followers: 40

Kudos [?]: 578 [1] , given: 32

Re: DS: Need explanation too [#permalink]

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22 Aug 2008, 12:30
1
KUDOS
A.

(1) Sufficient.

We know that ABD = 180 - x - ADB.

ADB = 180 - 2x because together the 2 angles make up a straight line that = 180.

so ABD = 180 - x - (180 - 2x)
ABD = 180 - x -180 + 2x
ABD = 180 - 180 - x +2x
ABD = x

This makes Triangle ABD an isosceles traingle. So If AD = 6, then DB = 6 and DB is part of another isosceles triangle (we know this because 2 angles are identical at 2x). So if DB is 6 and it's part of another isosceles triangle, then it's length will be equal to BC. So SUFFICIENT.

(2) All this tells us is the angle. It doesn't tell us anythign about a length so it will be insufficient.
_________________

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J Allen Morris
**I'm pretty sure I'm right, but then again, I'm just a guy with his head up his a$$. GMAT Club Premium Membership - big benefits and savings SVP Joined: 30 Apr 2008 Posts: 1887 Location: Oklahoma City Schools: Hard Knocks Followers: 40 Kudos [?]: 578 [0], given: 32 Re: DS: Need explanation too [#permalink] ### Show Tags 22 Aug 2008, 17:27 Would you please post the OA so that future forum users can benefit from this question. _________________ ------------------------------------ J Allen Morris **I'm pretty sure I'm right, but then again, I'm just a guy with his head up his a$$.

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Re: DS: Need explanation too   [#permalink] 22 Aug 2008, 17:27
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