Question about inversion images











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"Let $W$ be a circle with center $O$ and radius $r$. Let $S$ be a point outside
the circle. Let $l_1$ and $l_2$ be two tangent lines to the circle $W$ passing through the point $S$ . Let $T_1$ and $T_2$ be the points of tangency of these lines with the circle. Show that
the point of intersection of the segments $OS$ and $T_1$$T_2$ is the image of $S$ under inversion in $W$"






I really do not know how to get started with this question, apart from knowing that $OS$*$OS' = R^2$ where $R$ is the radius of the new circle. Help?










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    "Let $W$ be a circle with center $O$ and radius $r$. Let $S$ be a point outside
    the circle. Let $l_1$ and $l_2$ be two tangent lines to the circle $W$ passing through the point $S$ . Let $T_1$ and $T_2$ be the points of tangency of these lines with the circle. Show that
    the point of intersection of the segments $OS$ and $T_1$$T_2$ is the image of $S$ under inversion in $W$"






    I really do not know how to get started with this question, apart from knowing that $OS$*$OS' = R^2$ where $R$ is the radius of the new circle. Help?










    share|cite|improve this question


























      up vote
      0
      down vote

      favorite









      up vote
      0
      down vote

      favorite












      "Let $W$ be a circle with center $O$ and radius $r$. Let $S$ be a point outside
      the circle. Let $l_1$ and $l_2$ be two tangent lines to the circle $W$ passing through the point $S$ . Let $T_1$ and $T_2$ be the points of tangency of these lines with the circle. Show that
      the point of intersection of the segments $OS$ and $T_1$$T_2$ is the image of $S$ under inversion in $W$"






      I really do not know how to get started with this question, apart from knowing that $OS$*$OS' = R^2$ where $R$ is the radius of the new circle. Help?










      share|cite|improve this question
















      "Let $W$ be a circle with center $O$ and radius $r$. Let $S$ be a point outside
      the circle. Let $l_1$ and $l_2$ be two tangent lines to the circle $W$ passing through the point $S$ . Let $T_1$ and $T_2$ be the points of tangency of these lines with the circle. Show that
      the point of intersection of the segments $OS$ and $T_1$$T_2$ is the image of $S$ under inversion in $W$"






      I really do not know how to get started with this question, apart from knowing that $OS$*$OS' = R^2$ where $R$ is the radius of the new circle. Help?







      geometry linear-transformations euclidean-geometry transformation geometric-transformation






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      edited Nov 28 at 21:07









      greedoid

      36.7k114593




      36.7k114593










      asked Nov 28 at 21:01









      helpneeded

      897




      897






















          1 Answer
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          Let $X$ be an intersection point of $T_1T_2$ and $OS$. Since circle around $XT_1S$ touches $OT_1$ we have, by the PoP of $O$ with respect to that new circle:$$ r^2 =OT_1^2 = OC cdot OS$$
          and we are done.






          share|cite|improve this answer





















          • What does "PoP" stand for?
            – helpneeded
            Nov 29 at 0:27










          • Pover of the point
            – greedoid
            Nov 29 at 9:32











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          1 Answer
          1






          active

          oldest

          votes








          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes








          up vote
          1
          down vote



          accepted










          Let $X$ be an intersection point of $T_1T_2$ and $OS$. Since circle around $XT_1S$ touches $OT_1$ we have, by the PoP of $O$ with respect to that new circle:$$ r^2 =OT_1^2 = OC cdot OS$$
          and we are done.






          share|cite|improve this answer





















          • What does "PoP" stand for?
            – helpneeded
            Nov 29 at 0:27










          • Pover of the point
            – greedoid
            Nov 29 at 9:32















          up vote
          1
          down vote



          accepted










          Let $X$ be an intersection point of $T_1T_2$ and $OS$. Since circle around $XT_1S$ touches $OT_1$ we have, by the PoP of $O$ with respect to that new circle:$$ r^2 =OT_1^2 = OC cdot OS$$
          and we are done.






          share|cite|improve this answer





















          • What does "PoP" stand for?
            – helpneeded
            Nov 29 at 0:27










          • Pover of the point
            – greedoid
            Nov 29 at 9:32













          up vote
          1
          down vote



          accepted







          up vote
          1
          down vote



          accepted






          Let $X$ be an intersection point of $T_1T_2$ and $OS$. Since circle around $XT_1S$ touches $OT_1$ we have, by the PoP of $O$ with respect to that new circle:$$ r^2 =OT_1^2 = OC cdot OS$$
          and we are done.






          share|cite|improve this answer












          Let $X$ be an intersection point of $T_1T_2$ and $OS$. Since circle around $XT_1S$ touches $OT_1$ we have, by the PoP of $O$ with respect to that new circle:$$ r^2 =OT_1^2 = OC cdot OS$$
          and we are done.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Nov 28 at 21:07









          greedoid

          36.7k114593




          36.7k114593












          • What does "PoP" stand for?
            – helpneeded
            Nov 29 at 0:27










          • Pover of the point
            – greedoid
            Nov 29 at 9:32


















          • What does "PoP" stand for?
            – helpneeded
            Nov 29 at 0:27










          • Pover of the point
            – greedoid
            Nov 29 at 9:32
















          What does "PoP" stand for?
          – helpneeded
          Nov 29 at 0:27




          What does "PoP" stand for?
          – helpneeded
          Nov 29 at 0:27












          Pover of the point
          – greedoid
          Nov 29 at 9:32




          Pover of the point
          – greedoid
          Nov 29 at 9:32


















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