What is minimum radius of circle given chord length?

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What is minimum radius of circle given chord length (Fig.)



I started by setup two line perpendicular to each other.



And find out some area of triangle , then find radius of circle from triangle inscribe in circle formula.



I don't know how this could be correct answer please give any advice for me.



Thank you in advance.



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    up vote
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    What is minimum radius of circle given chord length (Fig.)



    I started by setup two line perpendicular to each other.



    And find out some area of triangle , then find radius of circle from triangle inscribe in circle formula.



    I don't know how this could be correct answer please give any advice for me.



    Thank you in advance.



    enter image description here







    share|cite|improve this question





















      up vote
      0
      down vote

      favorite









      up vote
      0
      down vote

      favorite











      What is minimum radius of circle given chord length (Fig.)



      I started by setup two line perpendicular to each other.



      And find out some area of triangle , then find radius of circle from triangle inscribe in circle formula.



      I don't know how this could be correct answer please give any advice for me.



      Thank you in advance.



      enter image description here







      share|cite|improve this question











      What is minimum radius of circle given chord length (Fig.)



      I started by setup two line perpendicular to each other.



      And find out some area of triangle , then find radius of circle from triangle inscribe in circle formula.



      I don't know how this could be correct answer please give any advice for me.



      Thank you in advance.



      enter image description here









      share|cite|improve this question










      share|cite|improve this question




      share|cite|improve this question









      asked Aug 2 at 18:50









      ABCDEFG user157844

      37429




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          If you don't know anything else about the two line segments $AB$, $AC$, and $CD$ except their lengths, then the minimum radius will be half the length of $AB$ (which at its longest is a diameter of the circle).



          So, $(1/2)(2+5) = 7/2.$






          share|cite|improve this answer

















          • 1




            We need to be a little careful here. Extending $overlineCD$ could possibly lead to a longer chord of the circle, and thus a larger minimum radius. Let's check: If the extension has length $x$, then the Power of a Point theorem says that $3x = 2cdot 5 = 10$, so that $x = 10/3$. Thus, the extended chord has length $3+10/3 = 19/3$, which is less than $7$, so your calculation works. (On the other hand, if we had, for instance, $|CD| = 1$, then its extended form would have had length $11$.)
            – Blue
            Aug 2 at 21:54











          Your Answer




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          1 Answer
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          up vote
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          down vote













          If you don't know anything else about the two line segments $AB$, $AC$, and $CD$ except their lengths, then the minimum radius will be half the length of $AB$ (which at its longest is a diameter of the circle).



          So, $(1/2)(2+5) = 7/2.$






          share|cite|improve this answer

















          • 1




            We need to be a little careful here. Extending $overlineCD$ could possibly lead to a longer chord of the circle, and thus a larger minimum radius. Let's check: If the extension has length $x$, then the Power of a Point theorem says that $3x = 2cdot 5 = 10$, so that $x = 10/3$. Thus, the extended chord has length $3+10/3 = 19/3$, which is less than $7$, so your calculation works. (On the other hand, if we had, for instance, $|CD| = 1$, then its extended form would have had length $11$.)
            – Blue
            Aug 2 at 21:54















          up vote
          1
          down vote













          If you don't know anything else about the two line segments $AB$, $AC$, and $CD$ except their lengths, then the minimum radius will be half the length of $AB$ (which at its longest is a diameter of the circle).



          So, $(1/2)(2+5) = 7/2.$






          share|cite|improve this answer

















          • 1




            We need to be a little careful here. Extending $overlineCD$ could possibly lead to a longer chord of the circle, and thus a larger minimum radius. Let's check: If the extension has length $x$, then the Power of a Point theorem says that $3x = 2cdot 5 = 10$, so that $x = 10/3$. Thus, the extended chord has length $3+10/3 = 19/3$, which is less than $7$, so your calculation works. (On the other hand, if we had, for instance, $|CD| = 1$, then its extended form would have had length $11$.)
            – Blue
            Aug 2 at 21:54













          up vote
          1
          down vote










          up vote
          1
          down vote









          If you don't know anything else about the two line segments $AB$, $AC$, and $CD$ except their lengths, then the minimum radius will be half the length of $AB$ (which at its longest is a diameter of the circle).



          So, $(1/2)(2+5) = 7/2.$






          share|cite|improve this answer













          If you don't know anything else about the two line segments $AB$, $AC$, and $CD$ except their lengths, then the minimum radius will be half the length of $AB$ (which at its longest is a diameter of the circle).



          So, $(1/2)(2+5) = 7/2.$







          share|cite|improve this answer













          share|cite|improve this answer



          share|cite|improve this answer











          answered Aug 2 at 19:41









          John

          21.9k32346




          21.9k32346







          • 1




            We need to be a little careful here. Extending $overlineCD$ could possibly lead to a longer chord of the circle, and thus a larger minimum radius. Let's check: If the extension has length $x$, then the Power of a Point theorem says that $3x = 2cdot 5 = 10$, so that $x = 10/3$. Thus, the extended chord has length $3+10/3 = 19/3$, which is less than $7$, so your calculation works. (On the other hand, if we had, for instance, $|CD| = 1$, then its extended form would have had length $11$.)
            – Blue
            Aug 2 at 21:54













          • 1




            We need to be a little careful here. Extending $overlineCD$ could possibly lead to a longer chord of the circle, and thus a larger minimum radius. Let's check: If the extension has length $x$, then the Power of a Point theorem says that $3x = 2cdot 5 = 10$, so that $x = 10/3$. Thus, the extended chord has length $3+10/3 = 19/3$, which is less than $7$, so your calculation works. (On the other hand, if we had, for instance, $|CD| = 1$, then its extended form would have had length $11$.)
            – Blue
            Aug 2 at 21:54








          1




          1




          We need to be a little careful here. Extending $overlineCD$ could possibly lead to a longer chord of the circle, and thus a larger minimum radius. Let's check: If the extension has length $x$, then the Power of a Point theorem says that $3x = 2cdot 5 = 10$, so that $x = 10/3$. Thus, the extended chord has length $3+10/3 = 19/3$, which is less than $7$, so your calculation works. (On the other hand, if we had, for instance, $|CD| = 1$, then its extended form would have had length $11$.)
          – Blue
          Aug 2 at 21:54





          We need to be a little careful here. Extending $overlineCD$ could possibly lead to a longer chord of the circle, and thus a larger minimum radius. Let's check: If the extension has length $x$, then the Power of a Point theorem says that $3x = 2cdot 5 = 10$, so that $x = 10/3$. Thus, the extended chord has length $3+10/3 = 19/3$, which is less than $7$, so your calculation works. (On the other hand, if we had, for instance, $|CD| = 1$, then its extended form would have had length $11$.)
          – Blue
          Aug 2 at 21:54













           

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