parabola, The length of the chord of the parabola y<sup>2</sup>=x which is bisected at the point (2,1) is?<

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Title: parabola

Question Details:

Posted On: Feb 14, 2012 12:11 AM

The length of the chord of the parabola y²=x which is bisected at the point (2,1) is?

a)5^1/2 b)4*3^1/2 c)3*3^1/2 d)2*5^1/2

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Answer Details:

Feb 14, 2012 05:11 AM

T = S₁

y-0.5(x+2) = 1^2 - 2 = -1

2y - x - 2 = -2

or, x = 2y

Put in the equation,

y^2 = 2y

or, y = 0 , 2

x = 0, 4

Points where the line cuts the parabola = (0,0), (4,2)

Length = sqrt(4^2 + 2^2) = sqrt(16+4) = sqrt(20) = 2*sqrt(5)

Option (d)

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