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the question

so i understand that there would be 13 dots within this circle and it needs 8 more (21 in total) points. The points that needed would be $(+/- 1, +/- 2), (+/- 2, +/- 1)$. but how do you work out the increase in radius needed?

also the answer is radius increase of $\sqrt 5 - 2$

user577215664
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Bettalion
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  • How far from the origin are your four added points? – TonyK Jun 17 '20 at 10:10
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    You are not attracting much interest because people do not like to click trough to find the question. Please type it up so your question is self contained. – Ross Millikan Jun 17 '20 at 13:46

1 Answers1

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I'm not sure if im suposed to delete the question or add the answer and leave it, but i found the answer.

As the minimum expansion would be at (+/−1,+/−2),(+/−2,+/−1), we can use Pythagoras's theorem to find the new radius.

eg/

2²+1²= r²

so the radius of the new circle would be √5

the increase in radius is therefore √5 - 2, which is the answer

Bettalion
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