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Source: — Data Sufficiency |
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by ershovici » Sun Nov 22, 2009 4:08 am
I can prove that statement 2 is sufficient, but still have a feeling that D should be the answer

ST1 can't solve for this atatement
ST 2 Since DE || CA the angles of this two triangles are equal. since CA and CB (both are radius) - angle CAB=CBA. So angle DBE=DEB and DE should be equal DB.
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by whuannou » Sun Nov 22, 2009 8:11 am
Statement 1 is not sufficient because even if angle BCA is fixed at 60 degrees, one can still make angle BDE vary.

As long as angle BDE is not fixed or length BE set, DE length can vary.

Do you agree ?
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by sunnyjohn » Mon Nov 30, 2009 11:24 pm
IMO: B
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by hongwang9703 » Fri Jul 30, 2010 2:37 pm
i think the answer should be D, and here are the reasons why, Statement A, by itself, should be sufficient.

DB is the diameter of the circle, thus making angle DEB 90 degrees. (from the properties of triangles in circles)

If x = 60, then angle cba and cab are both 60 degrees as well, because ca=cb, as both are radius.

thus we know that ANGLE DBE is a 30-60-90 triangle, therefore DE = 3.5SQRT(3)


however, if i am wrong, then i am wrong with respect to stating that angle DEB is 90 degrees. Maybe that rule only applies when the question explicitly states that the triangle is inscribed in a circle.

please let me know kind sir,miss.
i got utterly defeated by the gmat.
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by Brent@GMATPrepNow » Fri Jul 30, 2010 3:29 pm
adam15 wrote: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 = 60°

(2) DE || CA
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by nithi_mystics » Fri Jul 30, 2010 6:23 pm
hongwang9703 wrote:i think the answer should be D, and here are the reasons why, Statement A, by itself, should be sufficient.

DB is the diameter of the circle, thus making angle DEB 90 degrees. (from the properties of triangles in circles)

If x = 60, then angle cba and cab are both 60 degrees as well, because ca=cb, as both are radius.

thus we know that ANGLE DBE is a 30-60-90 triangle, therefore DE = 3.5SQRT(3)


however, if i am wrong, then i am wrong with respect to stating that angle DEB is 90 degrees. Maybe that rule only applies when the question explicitly states that the triangle is inscribed in a circle.

please let me know kind sir,miss.
This is true only if the point E lies on the circle.
Thanks
Nithi
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