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Geometry

by parulmahajan89 » Mon Aug 13, 2012 6:47 pm
the radius of a circle that centers at origin is 5, how many points on the circle have integer coordinates?
(A) 4
(B) 8
(C) 12
(D) 16
(E) 20

Please provide the explanation for this asap

Thank you
Parul
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by coolhabhi » Mon Aug 13, 2012 8:50 pm
Since centre of the circle is origin (0, 0) and radius is 5, we have x^2 + y^2 = 5^2 = 25.
So the possible values of (x, y) are (3, 4), (-3, 4), (3, -4), (-3, -4), (4, 3), (-4, 3), (4, -3), (-4, -3), (5, 0), (-5, 0), (0, 5), (0, -5)

=>12 points.

answer is C.
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by Anurag@Gurome » Tue Aug 14, 2012 5:58 pm
parulmahajan89 wrote:the radius of a circle that centers at origin is 5, how many points on the circle have integer coordinates?
(A) 4
(B) 8
(C) 12
(D) 16
(E) 20

Please provide the explanation for this asap

Thank you
Parul
See Rahul's explanation here: https://www.beatthegmat.com/points-on-circle-t69887.html
Anurag Mairal, Ph.D., MBA
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1-800-566-4043 (USA)

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