co-ordinate geometry.

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co-ordinate geometry.

by Md.Nazrul Islam » Sat Apr 07, 2012 8:50 pm
Given a circle on co-ordinate axis with origin (0,0) and radius 5.find the number of points we could find on the circle.

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by Shalabh's Quants » Sun Apr 08, 2012 5:23 am
Md.Nazrul Islam wrote:Given a circle on co-ordinate axis with origin (0,0) and radius 5.find the number of points we could find on the circle.
The problem is not put up completely. Something is missing.

It should be..

Given a circle on co-ordinate axis with origin (0,0) and radius 5.Find the number of point with integer values we could find on the circle.

Soln...

...So the eqn of circle would be x^2+y^2=25.

The approach is to get 25 as result of 'Sum of squares of 2 integers'

=> 25=0^2+5^2 => It yields 2 points [(0,5),(5,0)];
=> 25=5^2+0^2 => It yields 2 points [(0,-5),(-5,0)];
=> 25=3^2=4^2 => It yields 4 points [(3,4),(-3,4),(-3,-4),(3,-4)];
=> 25=4^2=3^2 => It yields 4 points [(4,3),(-4,3),(-4,-3),(4,-3)];

So total 12 points.
Shalabh Jain,
e-GMAT Instructor