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# Question on DS help page

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Intern
Joined: 13 Jun 2006
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Question on DS help page [#permalink]  13 Jun 2006, 14:46
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
The first question on the DS page is below. Why does it have to be a 3-4-5 and a 5-12-13 triangle? Why couldn't the 12 be the hypotnuse thus making the triangle have sides 5-10.9-12 since we do not know which sides are what, thus not giving us enough information to solve the problem?

Example 1. Triangle ABC has one angle equal to 90 degrees and AB equal to 5 inches, what is the area of ABC?

(1) BC = 4
(2) AC = 12
Apparently both answer choices are sufficient to answer the question, but in two cases, the numeric answer differs. In the first case we get a 3-4-5 triangle and in the second 5-12-13, thus area of ABC1 is 6 and ABC2 is 30.
VP
Joined: 29 Dec 2005
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Re: Question on DS help page [#permalink]  13 Jun 2006, 17:24
Alanjackson wrote:
Triangle ABC has one angle equal to 90 degrees and AB equal to 5 inches, what is the area of ABC?

(1) BC = 4
(2) AC = 12

it is not necessary to have 3-4-5 or 5-12-13 to have a right angle triangle if the given information is not sufficient as above. right angle triangle can have different measurements of sides. however, no matter the sides of the right angle triangle, it must hold a relationship of its sides as h^2 = l^2 + b^2.

the question seems poorly structured because st 1 and 2 each alone are not sufficient to find the area of the triangle. combined 1 and 2 also doesnot make any triangle.

H could have any value in 1 and 2. in 1, it could be 5 or sqrt(41). in 2, it could be 12 or 13.

so OA you have might be C but it doesnot make any sense.
CEO
Joined: 20 Nov 2005
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Schools: Completed at SAID BUSINESS SCHOOL, OXFORD - Class of 2008
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What a question:

St1: This leads to either 3-4-5 or 4-5-SQRT(41). INSUFF

St2: This leads to either 5-12-13 or 5- SQRT(119)-12 : INSUFF

Combined: 4-5-12 is not a triangle.
_________________

SAID BUSINESS SCHOOL, OXFORD - MBA CLASS OF 2008

SVP
Joined: 30 Mar 2006
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E
1) Not suff
We dont know 5 and 4 are what? base altitute or Hyp

2) Not suff
We dont know 5 and 12 are what? base altitute or Hyp

Together

5-4-12 is not a right triangle
Manager
Joined: 29 Sep 2005
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jaynayak wrote:
E
1) Not suff
We dont know 5 and 4 are what? base altitute or Hyp

2) Not suff
We dont know 5 and 12 are what? base altitute or Hyp

Together

5-4-12 is not a right triangle

I agree with E however,

1) We do know that 4 is either base or height (not the longest side)

What we do not know is what 5 is

2) We do know that 5 is either base or height not the longest side. we do not know what 12 is.

Combining 1 and 2 logically we get 4 from st 1 and 5 from st 2 and should be sufficient to find the area, however the pythagoras theorm does not hold.

I feel like the concepts being tested here are:

Base + Height > Hypo

Hypo is the longest side

Maybe someone else can shed some light?
So I would have to go with E.
Intern
Joined: 13 Jun 2006
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All very helpful. It appears that this should be switched to reflect your answers on the website. I think there is also an error on another one of the DS examples on the help page. I have just posted it as a new topic so please take a look at and help provide the right answer.
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