Geometry- Circles!

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Geometry- Circles!

by varun7nurav » Sun Sep 18, 2011 8:50 am
Hi guys... Im stuck with this Geometry problem. Just unable to know where to start from?
As it involves figures, I have taken a snapshot of the problem and attaching it as a figure. Please find attached the copy to view the problem.


Thank you!


Image
Source: — Problem Solving |

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by GMATGuruNY » Sun Sep 18, 2011 9:57 am
varun7nurav wrote: Image
The two triangles are similar. See below:

Image

An inscribed angle is formed by two chords.
Inscribed angles that intercept the same arc are equal.
Inscribed angles BCD and BED both intercept arc BD. Thus, angles BCE and BED are equal.
Inscribed angles CBE and CDE both intercept arc CE. Thus, angles CBE and CDE are equal.
Angles BAC and DAE are equal because they are vertical angles.
Thus, triangles ABC and DAE are similar.
Corresponding sides in similar triangles yield the same ratio.
Thus:
AB/AD = CB/DE
4/6 = 6/DE
DE = 9.

The correct answer is D.
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by varun7nurav » Sun Sep 18, 2011 10:27 am
Absolutely...!!! Thanks a ton!