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Analytical Geometry

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Joined:	24 Feb 2009
Post:	119

20 Mar 2009 09:12:23 IST

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298

parabola....

None

if two distinct chords of parabola y^2=4ax, is passing through (a,2a) are bisected by the line x+y=1.

then length of latus rectum can be.

a-2

b-4

c-5

d-6.

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Comments (1)

saharsha kumar keshkar

Forum Expert

Joined: 7 Aug 2008

Posts: 1104

20 Mar 2009 09:31:54 IST

Like 2 people liked this

it is a good question....

Any point on the line x+y=1 can be taken as (t , 1-t)

equation of chord with this as mid point is y(1-t)-2a(x+t)=(1-t)^2 -4at.

as..

it passes through (a ,2a....=>t²-2t+2a²-2a+1=0

we get two distinct roots...so a²-a<0

which gives,

0<a<1...

hence answer is (a)..

nudge me i m wrong.....

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