Co-ordinate Geometry

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Co-ordinate Geometry

by ankitns » Tue Aug 04, 2009 9:01 am
I came across a question that required me to consider all the points P(x,y) such that P lies on the circle with radius 10 and center (0,0). It is given that x and y are integers. It is given that P lies in quadrant 1.

Since the radius = 10; we can use the formula that x^2 + y^2 = 100.

I was not sure if the list would be:

A) (10,0), (0,10), (6,8) (8, 6)

or

B) (6,8) (8, 6)

Option A has two points that are on the axis and I was not sure if they are considered in quadrant 1.

Any ideas?

Thanks for the help.
Last edited by ankitns on Wed Aug 05, 2009 7:43 am, edited 1 time in total.
Attempt 1: 710, 92% (Q 42, 63%; V 44, 97%)
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Re: Co-ordinate Geometry

by quant-master » Tue Aug 04, 2009 12:30 pm
ankitns wrote:If a point lies on the axis, say point P(10,0) or Q (0,-10), which quadrant does it fall in (if any)? Is there a rule that states something like:

1) Point on X-Axis where x > 0 will fall in Quadrant 1
2) Point on X-Axis where x < 0 will fall in Quadrant 3

Or any gudilelines as such?

I came across a question that required me to consider all the points P(x,y) such that P lies on the circle with radius 10 and center (0,0). It is given that x and y are integers. It is given that P lies in quadrant 1.

Since the radius = 10; we can use the formula that x^2 + y^2 = 100.

I was not sure if the list would be:

A) (10,0), (0,10), (6,8) (8, 6)

or

B) (6,8) (8, 6)

Option A has two points that are on the axis and I was not sure if they are considered in quadrant 1.

Any ideas?

Thanks for the help.

Image

In the above image, you can see the four quadrants numbered I,II,III and IV.

Sign to each quadrant is assigned based on the sign of x and y axis. For example in quadrant I, this quadrant is enclosed by x axis on the bottom and y axis at the left. X axis which is moving towards right will have +ve numbers and Y axis moving upward will have +ve numbers hence (x,y) will be (+,+), similarly in the II quadrant (x,y) will be (-,+) x is -ve as it is moving left.

Hope this is clear.

Let me know if you need further clarification.

Thanks,
Quant-Master
https://gmat-quants.blocked - My Blog Updated almost daily with new quant fundas. Find collection of quants question in my blog

Senior | Next Rank: 100 Posts
Posts: 59
Joined: Mon Jul 13, 2009 8:58 pm
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Re: Co-ordinate Geometry

by ankitns » Tue Aug 04, 2009 1:31 pm
Appreciate it but I did know this and hence did not include points (-6,-8) or (-8,6) etc in the list as these are definitely not in quadrant 1...but my question still remains as to which quadrant is point (10, 0) or (0,10)?? Can you please clarify that? Will they be included in 1st quadrant?? Broader question is that if point is on the axis, is it or is it not inluded on any of the quadrants?

Thanks for the help.

quant-master wrote:
ankitns wrote:If a point lies on the axis, say point P(10,0) or Q (0,-10), which quadrant does it fall in (if any)? Is there a rule that states something like:

1) Point on X-Axis where x > 0 will fall in Quadrant 1
2) Point on X-Axis where x < 0 will fall in Quadrant 3

Or any gudilelines as such?

I came across a question that required me to consider all the points P(x,y) such that P lies on the circle with radius 10 and center (0,0). It is given that x and y are integers. It is given that P lies in quadrant 1.

Since the radius = 10; we can use the formula that x^2 + y^2 = 100.

I was not sure if the list would be:

A) (10,0), (0,10), (6,8) (8, 6)

or

B) (6,8) (8, 6)

Option A has two points that are on the axis and I was not sure if they are considered in quadrant 1.

Any ideas?

Thanks for the help.

Image

In the above image, you can see the four quadrants numbered I,II,III and IV.

Sign to each quadrant is assigned based on the sign of x and y axis. For example in quadrant I, this quadrant is enclosed by x axis on the bottom and y axis at the left. X axis which is moving towards right will have +ve numbers and Y axis moving upward will have +ve numbers hence (x,y) will be (+,+), similarly in the II quadrant (x,y) will be (-,+) x is -ve as it is moving left.

Hope this is clear.

Let me know if you need further clarification.

Thanks,
Quant-Master
Attempt 1: 710, 92% (Q 42, 63%; V 44, 97%)
Attempt 2: Coming soon!