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Source: — Data Sufficiency |
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Re: MGMAT question

by jayhawk2001 » Sat May 05, 2007 8:14 am
Is it E ?

ABC and DEC are similar triangles. So, AB/DE is some value x.

1 - insufficient. BE = 3 implies DE = 4 but we can't find AB from this
alone

2 - insufficient. Same reason as 1

1 and 2 together don't give you info that 1 alone or 2 alone doesn't
already give you.

Hence E?
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by jayhawk2001 » Sat May 05, 2007 9:13 am
Actually I think it should be D

There are multiple sets of similar triangles here

ABC and DEC
ABC and BDC

Using ABC and BDC, BD / DE = 5/4 = AB / BD

Since we know BD, we can compute AB.

As mentioned in my earlier post, DE can be computed using 1 or 2.

Hence D

OA please :-)
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by ns88 » Sun May 06, 2007 6:21 am
ans=D

By knowing BE or DE, we can extrapolate the angle BDE.

Thus we can see what angle ABD is and then angle BAD.
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by f2001290 » Tue May 08, 2007 12:09 am
Remember this formula for similar triangles

Ratio of sides = Ratio of heights = Ratio of Medians = Ration of Angular bisectors = Ratio of In-radius = Ratio of Circum radius.

In the problem, ABC and BDC are similar
so,

Ratio of sides = Ratio of heights

BD/AB = DE/DB
5/AB = 4/5

AB = 25/4
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by Stacey Koprince » Tue May 08, 2007 12:01 pm
Also remember that any time you have a right triangle and you drop a perpendicular height from the right angle (that is, you create two smaller right triangles out of the right angle of the big triangle), all 3 right triangles will be similar. This problem does so twice, so all of the right triangles are similar.
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by Cybermusings » Thu May 10, 2007 8:08 am
OA IS INDEED D

CHEERS
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by santosh_surathkal » Mon Mar 14, 2011 9:37 am
Cybermusings wrote:Please solve this DS question...and give detailed explanation!
Yes OA must be D.
As 3 right angles are similar we know BE =3 in case 1
and DE = 4 in case 2
if we take case 1 or case 2 individually we can find out all hands of triangle BDE.

Now as triangles are similar we can also find out AB in both the cases.
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