Manhattan GMAT CAT- Length of Line DE

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Misterbuff: Junior | Next Rank: 30 Posts; Posts: 11; Joined: Sat Aug 11, 2007 6:18 pm

by Misterbuff » Tue Sep 23, 2008 5:39 pm

Hi everyone,

Please see the attached problem. After reading the explanation Manhattan GMAT provided, I still believe I am correct. I would appreciate it if someone out there is able to provide a better explanation or maybe support my answer (D).

Thanks.

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Source: Beat The GMAT — Data Sufficiency | Tue Sep 23, 2008 5:39 pm

parallel_chase: Legendary Member; Posts: 1153; Joined: Wed Jun 20, 2007 6:21 amFollowed by: 2 members; Thanked: 146 times

Re: Manhattan GMAT CAT- Length of Line DE

by parallel_chase » Tue Sep 23, 2008 6:27 pm

Misterbuff wrote:Hi everyone,

Please see the attached problem. After reading the explanation Manhattan GMAT provided, I still believe I am correct. I would appreciate it if someone out there is able to provide a better explanation or maybe support my answer (D).

Thanks.

I think the answer should be B.

Statement I

insufficient because it does not tell us anything about other angles.

Statement II

We can determine that both triangles are similar triangle.
therefore DE= 7

Whats the OA?

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Misterbuff: Junior | Next Rank: 30 Posts; Posts: 11; Joined: Sat Aug 11, 2007 6:18 pm

by Misterbuff » Tue Sep 23, 2008 6:47 pm

Hmm, I just took another look at the problem and I now agree with the answer. Thanks for the help!

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nitin86: Master | Next Rank: 500 Posts; Posts: 111; Joined: Sat Sep 01, 2007 11:00 pm; Thanked: 4 times

Re: Manhattan GMAT CAT- Length of Line DE

by nitin86 » Wed Sep 24, 2008 10:05 am

parallel_chase wrote:
Misterbuff wrote:Hi everyone,

Please see the attached problem. After reading the explanation Manhattan GMAT provided, I still believe I am correct. I would appreciate it if someone out there is able to provide a better explanation or maybe support my answer (D).

Thanks.
I think the answer should be B.

Statement I

insufficient because it does not tell us anything about other angles.

Statement II

We can determine that both triangles are similar triangle.
therefore DE= 7

Whats the OA?

@paralle_chase,

Stmt 1 does tell us about the angle A and B. Because CA and CB are the radius of the circle, that mean CA = CB = r. And in triangle, ABC, angle C = x = 60, hence, angale A and angle B is also 60 degree.

Also, by same logic, triangle ABC becomes similar to triangle BDE

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parallel_chase: Legendary Member; Posts: 1153; Joined: Wed Jun 20, 2007 6:21 amFollowed by: 2 members; Thanked: 146 times

Re: Manhattan GMAT CAT- Length of Line DE

by parallel_chase » Wed Sep 24, 2008 10:41 am

nitin86 wrote: @paralle_chase,

Stmt 1 does tell us about the angle A and B. Because CA and CB are the radius of the circle, that mean CA = CB = r. And in triangle, ABC, angle C = x = 60, hence, angale A and angle B is also 60 degree.

True

Also, by same logic, triangle ABC becomes similar to triangle BDE

False, you cant assume that DE = BE

We know that angle B is 60, but we dont know about angle D and angle E. Hence Insufficient.

Let me know if you think otherwise

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