Find the equation of the circle given the tangent line, point on the circle, and the radius [closed]











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The problem was this: radius is $2$, tangent to the $x$ axis, passes through $(1, -1)$. I don't know how to solve this, and my math teacher didnt teach this yet.










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closed as off-topic by amWhy, Brahadeesh, Paul Frost, T. Bongers, José Carlos Santos Nov 18 at 23:29


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – amWhy, Brahadeesh, Paul Frost, T. Bongers, José Carlos Santos

If this question can be reworded to fit the rules in the help center, please edit the question.













  • "my math teacher didnt teach this yet" A teacher shouldn't have to teach the exact method of solving a specific problem in order to expect his / her students to solve it. You have likely been taught all the tools you need: You know what the equation of a circle looks like, and you've been taught how to solve equations. In this problem you've been given information you can enter directly into that equation in order to solve and figure out the parts you haven't been told. Try it out, see how far you get, then let us know where you're stuck.
    – Arthur
    Nov 18 at 10:25












  • The circle also passes through $(x,0)$.
    – Yadati Kiran
    Nov 18 at 10:49










  • $(x-h)^2 + (y-k)^2=2^2 $ How to find $(h,k)?$
    – Narasimham
    Nov 18 at 18:17












  • Hint: the center has coordinates $(a,2)$ or $(a,-2)$.
    – egreg
    Nov 18 at 23:30















up vote
0
down vote

favorite












The problem was this: radius is $2$, tangent to the $x$ axis, passes through $(1, -1)$. I don't know how to solve this, and my math teacher didnt teach this yet.










share|cite|improve this question















closed as off-topic by amWhy, Brahadeesh, Paul Frost, T. Bongers, José Carlos Santos Nov 18 at 23:29


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – amWhy, Brahadeesh, Paul Frost, T. Bongers, José Carlos Santos

If this question can be reworded to fit the rules in the help center, please edit the question.













  • "my math teacher didnt teach this yet" A teacher shouldn't have to teach the exact method of solving a specific problem in order to expect his / her students to solve it. You have likely been taught all the tools you need: You know what the equation of a circle looks like, and you've been taught how to solve equations. In this problem you've been given information you can enter directly into that equation in order to solve and figure out the parts you haven't been told. Try it out, see how far you get, then let us know where you're stuck.
    – Arthur
    Nov 18 at 10:25












  • The circle also passes through $(x,0)$.
    – Yadati Kiran
    Nov 18 at 10:49










  • $(x-h)^2 + (y-k)^2=2^2 $ How to find $(h,k)?$
    – Narasimham
    Nov 18 at 18:17












  • Hint: the center has coordinates $(a,2)$ or $(a,-2)$.
    – egreg
    Nov 18 at 23:30













up vote
0
down vote

favorite









up vote
0
down vote

favorite











The problem was this: radius is $2$, tangent to the $x$ axis, passes through $(1, -1)$. I don't know how to solve this, and my math teacher didnt teach this yet.










share|cite|improve this question















The problem was this: radius is $2$, tangent to the $x$ axis, passes through $(1, -1)$. I don't know how to solve this, and my math teacher didnt teach this yet.







circle






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edited Nov 18 at 10:47









Yadati Kiran

1,243417




1,243417










asked Nov 18 at 10:16









aki

41




41




closed as off-topic by amWhy, Brahadeesh, Paul Frost, T. Bongers, José Carlos Santos Nov 18 at 23:29


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – amWhy, Brahadeesh, Paul Frost, T. Bongers, José Carlos Santos

If this question can be reworded to fit the rules in the help center, please edit the question.




closed as off-topic by amWhy, Brahadeesh, Paul Frost, T. Bongers, José Carlos Santos Nov 18 at 23:29


This question appears to be off-topic. The users who voted to close gave this specific reason:


  • "This question is missing context or other details: Please improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – amWhy, Brahadeesh, Paul Frost, T. Bongers, José Carlos Santos

If this question can be reworded to fit the rules in the help center, please edit the question.












  • "my math teacher didnt teach this yet" A teacher shouldn't have to teach the exact method of solving a specific problem in order to expect his / her students to solve it. You have likely been taught all the tools you need: You know what the equation of a circle looks like, and you've been taught how to solve equations. In this problem you've been given information you can enter directly into that equation in order to solve and figure out the parts you haven't been told. Try it out, see how far you get, then let us know where you're stuck.
    – Arthur
    Nov 18 at 10:25












  • The circle also passes through $(x,0)$.
    – Yadati Kiran
    Nov 18 at 10:49










  • $(x-h)^2 + (y-k)^2=2^2 $ How to find $(h,k)?$
    – Narasimham
    Nov 18 at 18:17












  • Hint: the center has coordinates $(a,2)$ or $(a,-2)$.
    – egreg
    Nov 18 at 23:30


















  • "my math teacher didnt teach this yet" A teacher shouldn't have to teach the exact method of solving a specific problem in order to expect his / her students to solve it. You have likely been taught all the tools you need: You know what the equation of a circle looks like, and you've been taught how to solve equations. In this problem you've been given information you can enter directly into that equation in order to solve and figure out the parts you haven't been told. Try it out, see how far you get, then let us know where you're stuck.
    – Arthur
    Nov 18 at 10:25












  • The circle also passes through $(x,0)$.
    – Yadati Kiran
    Nov 18 at 10:49










  • $(x-h)^2 + (y-k)^2=2^2 $ How to find $(h,k)?$
    – Narasimham
    Nov 18 at 18:17












  • Hint: the center has coordinates $(a,2)$ or $(a,-2)$.
    – egreg
    Nov 18 at 23:30
















"my math teacher didnt teach this yet" A teacher shouldn't have to teach the exact method of solving a specific problem in order to expect his / her students to solve it. You have likely been taught all the tools you need: You know what the equation of a circle looks like, and you've been taught how to solve equations. In this problem you've been given information you can enter directly into that equation in order to solve and figure out the parts you haven't been told. Try it out, see how far you get, then let us know where you're stuck.
– Arthur
Nov 18 at 10:25






"my math teacher didnt teach this yet" A teacher shouldn't have to teach the exact method of solving a specific problem in order to expect his / her students to solve it. You have likely been taught all the tools you need: You know what the equation of a circle looks like, and you've been taught how to solve equations. In this problem you've been given information you can enter directly into that equation in order to solve and figure out the parts you haven't been told. Try it out, see how far you get, then let us know where you're stuck.
– Arthur
Nov 18 at 10:25














The circle also passes through $(x,0)$.
– Yadati Kiran
Nov 18 at 10:49




The circle also passes through $(x,0)$.
– Yadati Kiran
Nov 18 at 10:49












$(x-h)^2 + (y-k)^2=2^2 $ How to find $(h,k)?$
– Narasimham
Nov 18 at 18:17






$(x-h)^2 + (y-k)^2=2^2 $ How to find $(h,k)?$
– Narasimham
Nov 18 at 18:17














Hint: the center has coordinates $(a,2)$ or $(a,-2)$.
– egreg
Nov 18 at 23:30




Hint: the center has coordinates $(a,2)$ or $(a,-2)$.
– egreg
Nov 18 at 23:30










2 Answers
2






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Given the conditions you gave, there is only two circle that works: their center is $left(begin{array}{cc} 1-sqrt{3}\ -2 end{array}right)$ and $left(begin{array}{cc} 1+sqrt{3}\ -2 end{array}right)$, their radius is $2$.



So their respective equation are:



$(x - 1+sqrt{3})^2 + (y+2)^2 = 4$ and $(x-1-sqrt{3})^2 + (y+2)^2 = 4$.






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    Since the circle is tangent to the x-axis and passes through $(1,-1)$ with radius $2$ we know the center is below the x-axis and $2$ units away from it.



    Thus the center is a point $ C(x,-2)$ which is $2$ unit apart from $(1,-1)$



    That gives us $$(x-1)^2 + (-1)^2 =4$$ which implies $x=1pm sqrt 3 $



    There are two circles with equations $$(x-1pm sqrt 3)^2 +(y+2)^2=4$$






    share|cite|improve this answer




























      2 Answers
      2






      active

      oldest

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      2 Answers
      2






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes








      up vote
      1
      down vote













      Given the conditions you gave, there is only two circle that works: their center is $left(begin{array}{cc} 1-sqrt{3}\ -2 end{array}right)$ and $left(begin{array}{cc} 1+sqrt{3}\ -2 end{array}right)$, their radius is $2$.



      So their respective equation are:



      $(x - 1+sqrt{3})^2 + (y+2)^2 = 4$ and $(x-1-sqrt{3})^2 + (y+2)^2 = 4$.






      share|cite|improve this answer



























        up vote
        1
        down vote













        Given the conditions you gave, there is only two circle that works: their center is $left(begin{array}{cc} 1-sqrt{3}\ -2 end{array}right)$ and $left(begin{array}{cc} 1+sqrt{3}\ -2 end{array}right)$, their radius is $2$.



        So their respective equation are:



        $(x - 1+sqrt{3})^2 + (y+2)^2 = 4$ and $(x-1-sqrt{3})^2 + (y+2)^2 = 4$.






        share|cite|improve this answer

























          up vote
          1
          down vote










          up vote
          1
          down vote









          Given the conditions you gave, there is only two circle that works: their center is $left(begin{array}{cc} 1-sqrt{3}\ -2 end{array}right)$ and $left(begin{array}{cc} 1+sqrt{3}\ -2 end{array}right)$, their radius is $2$.



          So their respective equation are:



          $(x - 1+sqrt{3})^2 + (y+2)^2 = 4$ and $(x-1-sqrt{3})^2 + (y+2)^2 = 4$.






          share|cite|improve this answer














          Given the conditions you gave, there is only two circle that works: their center is $left(begin{array}{cc} 1-sqrt{3}\ -2 end{array}right)$ and $left(begin{array}{cc} 1+sqrt{3}\ -2 end{array}right)$, their radius is $2$.



          So their respective equation are:



          $(x - 1+sqrt{3})^2 + (y+2)^2 = 4$ and $(x-1-sqrt{3})^2 + (y+2)^2 = 4$.







          share|cite|improve this answer














          share|cite|improve this answer



          share|cite|improve this answer








          edited Nov 18 at 11:33

























          answered Nov 18 at 10:49









          Euler Pythagoras

          4249




          4249






















              up vote
              0
              down vote













              Since the circle is tangent to the x-axis and passes through $(1,-1)$ with radius $2$ we know the center is below the x-axis and $2$ units away from it.



              Thus the center is a point $ C(x,-2)$ which is $2$ unit apart from $(1,-1)$



              That gives us $$(x-1)^2 + (-1)^2 =4$$ which implies $x=1pm sqrt 3 $



              There are two circles with equations $$(x-1pm sqrt 3)^2 +(y+2)^2=4$$






              share|cite|improve this answer

























                up vote
                0
                down vote













                Since the circle is tangent to the x-axis and passes through $(1,-1)$ with radius $2$ we know the center is below the x-axis and $2$ units away from it.



                Thus the center is a point $ C(x,-2)$ which is $2$ unit apart from $(1,-1)$



                That gives us $$(x-1)^2 + (-1)^2 =4$$ which implies $x=1pm sqrt 3 $



                There are two circles with equations $$(x-1pm sqrt 3)^2 +(y+2)^2=4$$






                share|cite|improve this answer























                  up vote
                  0
                  down vote










                  up vote
                  0
                  down vote









                  Since the circle is tangent to the x-axis and passes through $(1,-1)$ with radius $2$ we know the center is below the x-axis and $2$ units away from it.



                  Thus the center is a point $ C(x,-2)$ which is $2$ unit apart from $(1,-1)$



                  That gives us $$(x-1)^2 + (-1)^2 =4$$ which implies $x=1pm sqrt 3 $



                  There are two circles with equations $$(x-1pm sqrt 3)^2 +(y+2)^2=4$$






                  share|cite|improve this answer












                  Since the circle is tangent to the x-axis and passes through $(1,-1)$ with radius $2$ we know the center is below the x-axis and $2$ units away from it.



                  Thus the center is a point $ C(x,-2)$ which is $2$ unit apart from $(1,-1)$



                  That gives us $$(x-1)^2 + (-1)^2 =4$$ which implies $x=1pm sqrt 3 $



                  There are two circles with equations $$(x-1pm sqrt 3)^2 +(y+2)^2=4$$







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered Nov 18 at 11:52









                  Mohammad Riazi-Kermani

                  40.3k41958




                  40.3k41958















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