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Algebra

Blazing goIITian

Joined:	27 Jul 2007
Post:	3134

26 Dec 2008 18:12:15 IST

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469

Geometry ques...

None

ABCD is a rectangle. DE,EF and DF are drawn such that area of AED=5, area of BEF=4, area of CFD=3. If the area of triangle DEF be expressed as , where, , then x= ?

A-72

B-75

C-84

D-96

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Tarin Bansal

Blazing goIITian

Joined: 27 Jul 2007

Posts: 3134

27 Dec 2008 12:04:58 IST

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Someone plz reply........

Soumik

Blazing goIITian

Joined: 31 Jul 2008

Posts: 1266

27 Dec 2008 23:04:58 IST

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Ans is 84.

Take sides of rect. as p,q.

Take a = pq

x^1/2=2(21)^1/2

x=84.

Try it urself, it's a bare outline.

Tarin Bansal

Blazing goIITian

Joined: 27 Jul 2007

Posts: 3134

27 Dec 2008 23:25:38 IST

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Hey, how did u get that root21??

Soumik

Blazing goIITian

Joined: 31 Jul 2008

Posts: 1266

28 Dec 2008 22:55:03 IST

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$\ AD=x \\ \ CD=y\\ \frac{6}{y}=CF\\ \implies\ BF = \frac{xy-6}{y}$

Similarly repeat the same for the other sides, frame quad in xy and solve.

Simple!

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