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Cordinate Geometry

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by heshamelaziry » Thu Aug 27, 2009 5:46 pm
In the xy plane, each point on the circle K has non-negative coordinates and center of K is point (4,7), what is the maximum area for K ???

Answer: 16 * 3.14

Please explain
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Source: — Problem Solving |

by GambitOS » Thu Aug 27, 2009 10:42 pm
In x/y coordinate system the radius of the circle K will be x(4) - the closets point to the negative part. So we know the radius and we know that

Area of the circle = pi*r^2
Area=pi(3,14)*4^2=3,14*16

Could I ask you what is the sourse of the question?
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by heshamelaziry » Thu Aug 27, 2009 11:03 pm
GambitOS wrote:In x/y coordinate system the radius of the circle K will be x(4) - the closets point to the negative part. So we know the radius and we know that

Area of the circle = pi*r^2
Area=pi(3,14)*4^2=3,14*16

Could I ask you what is the sourse of the question?


What do you mean by "the closes point to the negative part" ? The problem here is whether the circle is touching x-axis, y-axis or just in quadrant one and not touching either.

This problem from www.mba.com free tests.

Thanks,
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Re: Cordinate Geometry

by winnerhere » Fri Aug 28, 2009 12:34 am
heshamelaziry wrote:In the xy plane, each point on the circle K has non-negative coordinates and center of K is point (4,7), what is the maximum area for K ???

Answer: 16 * 3.14

Please explain
If u draw a circle with radius 4,it will touch the y axis...just picturise it.

U cant go beyond x axis as all co ordinates are positive.

so maximum radius is 4 and maximum area is 16 * 3.14
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