On the coordinate plane (6, 2) and (0, 6)

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On the coordinate plane (6, 2) and (0, 6)

by abhi332 » Wed Feb 24, 2010 12:01 pm
On the coordinate plane (6, 2) and (0, 6) are the endpoints of the diagonal of a square. What is the distance between point (0, 0) and the closest vertex of the square?

(A) 1/sqrt (2)
(B) 1
(C) sqrt (2)
(D) sqrt (3)
(E) 2*sqrt (3)
[spoiler]
OA : C[/spoiler]
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by ajith » Wed Feb 24, 2010 9:22 pm
abhi332 wrote:On the coordinate plane (6, 2) and (0, 6) are the endpoints of the diagonal of a square. What is the distance between point (0, 0) and the closest vertex of the square?

(A) 1/sqrt (2)
(B) 1
(C) sqrt (2)
(D) sqrt (3)
(E) 2*sqrt (3)
[spoiler]
OA : C[/spoiler]
Equation of the diagonal x-6/(6) = y-2/(-4)

-4x+24 = 6y -12
2x+3y -18 =0

The other diagonal will be perpendicular to the first and bisects the first at (3,4)

the equation is 3x-2y +c =0
since it passes through (3,4) 3*3-2*4 +c =0
c = 1
2x-3y= -1

Half the length of the diagonal = sqrt(3^2+2^2) (distance from (3,4) to (0,6))

Now we have to find a point which is at sqrt(3^2+2^2) distance from (3,4) on the line 2x-3y= -1

(1,1) and (4,7) fits the bill of which, (1,1) is closer to the origin

Distance of (1,1) to the origin = sqrt(1^2+1^2) =[spoiler]sqrt(2)[/spoiler]

[spoiler]This is neither an elegant method nor an easy method![/spoiler]
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by bigmonkey31 » Wed Feb 24, 2010 11:34 pm
any better way to eliminate answer choices to guess strategically?