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chaitanya.mehrotra: Master | Next Rank: 500 Posts; Posts: 184; Joined: Thu Nov 25, 2010 9:57 pmFollowed by: 5 members; Thanked: 1 times; GMAT Score:700

by chaitanya.mehrotra » Sun Jul 24, 2011 12:22 pm

In the figure to the right, if point C is the center of the circle and DB = 7, what is the length of DE in triangle EDB?

(1) x = 60Â°

(2) DE || CA

OA after some discussion

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Source: Beat The GMAT — Data Sufficiency | Sun Jul 24, 2011 12:22 pm

clock60: Legendary Member; Posts: 759; Joined: Mon Apr 26, 2010 10:15 amFollowed by: 3 members; Thanked: 85 times

by clock60 » Sun Jul 24, 2011 12:44 pm

B for me, if DE||CA, then triangles DEB and CAB are similar, so DE is also 7.

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ColumbiaVC: Senior | Next Rank: 100 Posts; Posts: 93; Joined: Sun Jul 17, 2011 10:30 amFollowed by: 2 members; Thanked: 1 times

by ColumbiaVC » Sun Jul 24, 2011 8:29 pm

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Ozlemg: Master | Next Rank: 500 Posts; Posts: 407; Joined: Tue Jan 25, 2011 9:19 amFollowed by: 7 members; Thanked: 25 times

by Ozlemg » Mon Jul 25, 2011 12:23 am

IMO D.

Statement 1 helps us to figure out that AC // DE. So we can solve the prolem.

Statement 2 is also sufficient. (Property of similarity in triangles)

Thanks

The more you suffer before the test, the less you will do so in the test!

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clock60: Legendary Member; Posts: 759; Joined: Mon Apr 26, 2010 10:15 amFollowed by: 3 members; Thanked: 85 times

by clock60 » Mon Jul 25, 2011 8:52 am

Ozlemg wrote:IMO D.

Statement 1 helps us to figure out that AC // DE. So we can solve the prolem.

Statement 2 is also sufficient. (Property of similarity in triangles)

Thanks

hi Ozlemg
can you elaborate how you established that AC||DE using st 1?i am a bit confused
thanks

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edge: Senior | Next Rank: 100 Posts; Posts: 49; Joined: Sun Jun 26, 2011 5:45 pm; Thanked: 2 times

by edge » Mon Jul 25, 2011 6:12 pm

Ozlemg wrote:IMO D.

Statement 1 helps us to figure out that AC // DE. So we can solve the prolem.

It doesn't. Yes, internal angles of triangle ABC are 60Â° each, but try to visualize 'E' as just beyond 'A' on BA. It doesn't violate Statement 1, and DE != 7.

The correct answer is B.

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sandeep1306: Senior | Next Rank: 100 Posts; Posts: 39; Joined: Wed Jan 19, 2011 7:57 am; Location: bangalore

by sandeep1306 » Mon Jul 25, 2011 10:55 pm

Indeed the correct answer is B
in order to determine the length of DE, the only way is to figure out whether DE is parallel AC.
option 1 doesnt reveal this.
option 2 gives us the answer.

just for info , if DE//AC and AB:AD =m:n
Then,

AC = m/(m+n) DE

Thanks,
Sandeep

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