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two points in a plane

by sanju09 » Tue Jul 27, 2010 6:35 am
A, B are two points in a plane. If co-ordinates of B are (2, 4), what are the co-ordinates of point A?
(1) Slope of AB is 4.
(2) Length of AB is 2 Units.

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by kvcpk » Tue Jul 27, 2010 6:42 am
A, B are two points in a plane. If co-ordinates of B are (2, 4), what are the co-ordinates of point A?
(1) Slope of AB is 4.

y-4 = 4(x-2)

many (x,y) are possible.

(2) Length of AB is 2 Units.

Many points can be at 2 units distance from 2,4
Combining:

We know the line and we know the distance is 2 units from 2,4
But we dont know on which side.. Hence INSUFF

pick E
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by selango » Tue Jul 27, 2010 7:16 am
kvcpk wrote:A, B are two points in a plane. If co-ordinates of B are (2, 4), what are the co-ordinates of point A?
(1) Slope of AB is 4.

y-4 = 4(x-2)

many (x,y) are possible.

(2) Length of AB is 2 Units.

Many points can be at 2 units distance from 2,4
Combining:

We know the line and we know the distance is 2 units from 2,4
But we dont know on which side.. Hence INSUFF

pick E
Praveen,

Length of AB=4

It means distance between A and B

sqrt[(y-4)^2+(x-2)^2]=2

Please correct me if I am wrong..
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by arora007 » Tue Jul 27, 2010 9:56 am
These days i am preparing only the verbal stuff... don't know how I landed on this post...

now its obvious that cases A and B are out....

and A has to be a single point... which can't be... as on a line in a plane.. there shall be 2 points equidistant at 2 units....

and the question asks in plain english

"A, B are two points in a plane"

about the 1 point A & not 2, so my choice would be E.
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by kvcpk » Tue Jul 27, 2010 10:21 am
selango wrote: Praveen,

Length of AB=4

It means distance between A and B

sqrt[(y-4)^2+(x-2)^2]=2

Please correct me if I am wrong..
Hi Anand,

It is given that Slope of AB=4, not length.
Did I misinterpret your question?
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by selango » Tue Jul 27, 2010 10:28 am
kvcpk wrote:
selango wrote: Praveen,

Length of AB=4

It means distance between A and B

sqrt[(y-4)^2+(x-2)^2]=2

Please correct me if I am wrong..
Hi Anand,

It is given that Slope of AB=4, not length.
Did I misinterpret your question?
I have posted it incorrectly.

Praveen,

Length of AB=2

It means distance between A and B

sqrt[(y-4)^2+(x-2)^2]=2

Am I right?
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by kvcpk » Tue Jul 27, 2010 10:32 am
selango wrote:I have posted it incorrectly.

Praveen,

Length of AB=2

It means distance between A and B

sqrt[(y-4)^2+(x-2)^2]=2

Am I right?
Yeah.. You are right.. But we can get more than 1 value for (x,y).

Logically, statement 2 is saying that a point is 2 units from a given point.
WHich means that it can fall on the circle around it with 2 units as radius.

That is the reason I did not use the formula.
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by selango » Tue Jul 27, 2010 10:38 am
Got it..Thanks buddy:)
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by arora007 » Tue Jul 27, 2010 11:01 am
kvcpk wrote:
selango wrote:I have posted it incorrectly.

Praveen,

Length of AB=2

It means distance between A and B

sqrt[(y-4)^2+(x-2)^2]=2

Am I right?
Yeah.. You are right.. But we can get more than 1 value for (x,y).

Logically, statement 2 is saying that a point is 2 units from a given point.
WHich means that it can fall on the circle around it with 2 units as radius.

That is the reason I did not use the formula.
yeah Circle in the plane... but 2 points on that line..
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by outreach » Tue Jul 27, 2010 11:48 am
one Question

eq of line is given by y=mx+c
stmt1 can be written as
y-4 = 4(x-2)
y=4x-6
y/-6 -x/(4/6) =1 shd give us the x and y intercept..where am i wrong?
kvcpk wrote:A, B are two points in a plane. If co-ordinates of B are (2, 4), what are the co-ordinates of point A?
(1) Slope of AB is 4.

y-4 = 4(x-2)

many (x,y) are possible.

(2) Length of AB is 2 Units.

Many points can be at 2 units distance from 2,4
Combining:

We know the line and we know the distance is 2 units from 2,4
But we dont know on which side.. Hence INSUFF

pick E
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by kvcpk » Tue Jul 27, 2010 11:56 am
outreach wrote:one Question

eq of line is given by y=mx+c
stmt1 can be written as
y-4 = 4(x-2)
y=4x-6
y/-6 -x/(4/6) =1 shd give us the x and y intercept..where am i wrong?
A,B are any 2 points on the plane.
We need to pin point a (x,y) which can satisfy the conditions.

There are more than one value for x,y here.

Hope this heps!!
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by outreach » Tue Jul 27, 2010 12:02 pm
got it
we are getting the equation of line AB and not specific points
kvcpk wrote:
outreach wrote:one Question

eq of line is given by y=mx+c
stmt1 can be written as
y-4 = 4(x-2)
y=4x-6
y/-6 -x/(4/6) =1 shd give us the x and y intercept..where am i wrong?
A,B are any 2 points on the plane.
We need to pin point a (x,y) which can satisfy the conditions.

There are more than one value for x,y here.

Hope this heps!!
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by kvcpk » Tue Jul 27, 2010 12:04 pm
outreach wrote:got it
we are getting the equation of line AB and not specific points
kvcpk wrote:
outreach wrote:one Question

eq of line is given by y=mx+c
stmt1 can be written as
y-4 = 4(x-2)
y=4x-6
y/-6 -x/(4/6) =1 shd give us the x and y intercept..where am i wrong?
A,B are any 2 points on the plane.
We need to pin point a (x,y) which can satisfy the conditions.

There are more than one value for x,y here.

Hope this heps!!
Exactly :)
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