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Elementary Geometry

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by Aman verma » Fri May 21, 2010 8:53 am
Q: A triangle is formed by joining three points P , Q , R on sides AB , BC , CA respectively of Triangle ABC . Then what is the area of Triangle ABC ?

I. The area of Triangle PQR is 6 cm^2

II. P, Q, R are the mid points of the sides AB , BC , CA respectively.
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Source: — Data Sufficiency |

by liferocks » Fri May 21, 2010 8:58 am
From 1
we know the area of PRQ but no info about the relation between triangle ABC and PQR...not sufficient

From 2
Since P, Q, R are the mid points of the sides AB , BC , CA respectively ,area of triangle pqr=1/4th of area of ABC
but no info on area of PRQ...not sufficient

combining area of ABC=4*area of PQR=24..sufficient

Ans option C
"If you don't know where you are going, any road will get you there."
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by gmatmachoman » Fri May 21, 2010 9:48 am
liferocks wrote:From 1
we know the area of PRQ but no info about the relation between triangle ABC and PQR...not sufficient

From 2
Since P, Q, R are the mid points of the sides AB , BC , CA respectively ,area of triangle pqr=1/4th of area of ABC
but no info on area of PRQ...not sufficient

combining area of ABC=4*area of PQR=24..sufficient

Ans option C
Agreed that C is the best option... Now that can u plz tell me how u arrived that PQR is similar to ABC...Just got rusty with basics of similarity!!

I am aware that ration of areas of similar triangles is square of the ratio of the proportional sides..

But plz do let me how PQR & ABC became similar...( I am know its is similar...but forgot the path)
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by liferocks » Fri May 21, 2010 6:32 pm
attached the explanation... sorry for the horrible handwriting and image...but I am really lazy to draw online .And for proving pqr similar to ABC..try using the parallel lines.

Image
"If you don't know where you are going, any road will get you there."
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by gmatmachoman » Fri May 21, 2010 9:04 pm
@LR "sis" (hahahhaa...Remember that???) Congrats for scoring half a ton Thanks....

Yeah thx for the explanation.!
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by liferocks » Sat May 22, 2010 4:04 am
gmatmachoman wrote:@LR "sis" (hahahhaa...Remember that???) Congrats for scoring half a ton Thanks....

Yeah thx for the explanation.!
You are welcome govardhan sir!!
"If you don't know where you are going, any road will get you there."
Lewis Carroll
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by Aman verma » Sun May 23, 2010 8:28 am
OAC.
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