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Ravshonbek
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another traingle 30 Aug 2007, 14:33
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another one

explain plz



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IrinaOK
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another traingle 30 Aug 2007, 15:43
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Ravshonbek
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explain plz
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I keep getting sqrt (2)-1/2

which is approximately 9/10

the area of big triangle is (sqrt2)^2/2=1
the area of small if (sqrt2-1)^2/2= 1-srt(2)+1/2

1-1+sqrt(2)-1/2=9/10

what am I missing?
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bkk145
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another traingle 30 Aug 2007, 15:50
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Ravshonbek
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explain plz
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E.

Knowing PS=2, and it is 45-45-90 triangle, you can get the sides PT and TS by using the 45-45-90 relationship:
So PT=TS= 2/sqrt(2)
Area of PST = 1/2 * 2/sqrt(2) * 2/sqrt(2) = 1

Knowing QR=1, you can assume (I think you can assume this ) that PU=1, sp Area PUR = 1/2 * 1 *1 = 1/2

Area of the shaded = 1- 1/2 = 1/2
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IrinaOK
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another traingle 30 Aug 2007, 16:05
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Ravshonbek
another one

explain plz

E.

Knowing PS=2, and it is 45-45-90 triangle, you can get the sides PT and TS by using the 45-45-90 relationship:
So PT=TS= 2/sqrt(2)
Area of PST = 1/2 * 2/sqrt(2) * 2/sqrt(2) = 1

Knowing QR=1, you can assume (I think you can assume this ) that PU=1, sp Area PUR = 1/2 * 1 *1 = 1/2

Area of the shaded = 1- 1/2 = 1/2
Show more


for the text in bold to be correct UR=1 also must be asummed

PU= 1 may be logically assumed, but what makes the assumption UR=1 correct?

Right I got it,

The small and big triangles are similar, so the ratio of correspoding sides is the same.
My first my equation was wrong.
this is correct

PU/PT=UR/RS
1/sqrt2=UR/sqrt2-------> UR =1

Answer is E
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another traingle 30 Aug 2007, 16:16
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IrinaOK
bkk145
Ravshonbek
another one

explain plz

E.

Knowing PS=2, and it is 45-45-90 triangle, you can get the sides PT and TS by using the 45-45-90 relationship:
So PT=TS= 2/sqrt(2)
Area of PST = 1/2 * 2/sqrt(2) * 2/sqrt(2) = 1

Knowing QR=1, you can assume (I think you can assume this ) that PU=1, sp Area PUR = 1/2 * 1 *1 = 1/2

Area of the shaded = 1- 1/2 = 1/2

for the text in bold to be correct UR=1 also must be asummed

PU= 1 may be logically assumed, but what makes the assumption UR=1 correct?

Right I got it,

The small and big triangles are similar, so the ratio os correspoding sides is the same.
In my first my equation was wrong.
this is correct

PU/PT=UR/RS
1/sqrt2=UR/sqrt2-------> UR =1

Answer is E
Show more


If I assumed PU =1, then it follows that angle QPU = RUP = 90. I know it is a lot of assumption, but this is the only way that I can logically assume that PU=1.
So you have another 45-45-90 triangle; thus, UR = 1
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another traingle 30 Aug 2007, 16:34
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Guys thanks a ton for hard work.

OA is E.

in gmat better not to assume but use rules.
Bkk used "birds eye" which is time saving



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Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
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