GMAT Powerprep Geometry Question

This topic has expert replies
Senior | Next Rank: 100 Posts
Posts: 66
Joined: Sat Sep 29, 2007 7:17 pm
Thanked: 5 times
GMAT Score:660

GMAT Powerprep Geometry Question

by ssy » Sun Oct 14, 2007 7:20 am
Geometry question, please help..

Rough image of the triangle is attached, sorry, I do not know how to post it on here. Triangle BCD is probably an isoceles triangle as two of its angles have the same angles.

In triangle ABC, what is the length of BC?

1) Length of AD=6

B) X= 36

[Ans: A, the first statement is sufficient.][/img]
Attachments
Presentation3.jpg

Master | Next Rank: 500 Posts
Posts: 127
Joined: Tue Oct 02, 2007 9:35 am
Thanked: 1 times

by arocks » Sun Oct 14, 2007 12:34 pm
In triangle adc,
angle BAD=x
angle BDA=180-2x
angle ABD=180-BAD-BDA = 180-x-180+2x = x
so angle BAD=angle ABD; side AD= side BD=6

In triangle bdc,
BD=BC; so, BD=6=BC

So stmt1 is suff.

stmt2 does not give the length of any relevant side, so it is not possible to calculate BC. Insuff.

ANS: A

P.S. - One easy way to capture image while giving the GMATPrep is to use printscreen (PrtSc key on the top right of the keyboard) and then paste the image in Paint. That would prevent you from further drawings;)

Senior | Next Rank: 100 Posts
Posts: 66
Joined: Sat Sep 29, 2007 7:17 pm
Thanked: 5 times
GMAT Score:660

by ssy » Sun Oct 14, 2007 9:14 pm
Arocks - Thanks so much, this question had me puzzled all night!