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Isosceles triangle

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Isosceles triangle

by expert » Mon Apr 06, 2009 9:20 pm
Hi guys. I recently started preparing for GMAT and I am shocked how frustrating data sufficiency questions are (for me). Very often I simply don't get the question right. Here is one of them. It's a question from GMAT Prep software

Image

It is simple as 2*2=4 but still I managed to fail it.

Could you please tell me why (2) is not sufficient ? Isosceles triangle always has following angles: x, x and (180 - 2*x). It should be enough to know single angle to find out two remaining.

Thank you.
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by sacx » Tue Apr 07, 2009 1:26 am
expert wrote:Hi guys. I recently started preparing for GMAT and I am shocked how frustrating data sufficiency questions are (for me). Very often I simply don't get the question right. Here is one of them. It's a question from GMAT Prep software

Image

It is simple as 2*2=4 but still I managed to fail it.

Could you please tell me why (2) is not sufficient ? Isosceles triangle always has following angles: x, x and (180 - 2*x). It should be enough to know single angle to find out two remaining.

Thank you.
yes you are right the measure of angles for issoscles triangle is x,x,180-2x

BUT the question asks measure of angle R and the statement II says angle S = 40, so we cannot determine if angle T is 40 or R = 40
SACX
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by sanju09 » Tue Apr 07, 2009 5:15 am
Hope you got it from sacx, expert! What do you do to paste the question from a prep source as it is, as you done here? Please explain!
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by expert » Tue Apr 07, 2009 7:40 am
sacx, you're right. After posting this I realized that with 40 degrees we don't know which angle they're talking about. For some reason I had wrongful assumption that order of letters in naming of the triangle defines the angle formed by two equal sides.

sanju09, I took a screenshot of the question by pressing Ctrl+PrtSc, then cropped it in my image viewer and uploaded it to free hosting service (radikal.ru in my case, but you can use tinypic.com and others).
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