find a circle given two tangent points and angles












0














I've searched and found similar questions, but with less information given, and I was hoping that the additional information would allow for a more streamlined solution.



Given two points, and their tangent angles (not sure if that's the proper term), what's the fewest number of steps to get the center and radius of the circle?



Circle given the information indicated










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  • What exactly do you mean by fewest number of steps?
    – Mike Pierce
    Nov 24 at 2:14






  • 1




    Having the tangent angles and the points, you basically have two lines that are tangent to the circle. You can construct the lines that are perpendicular to each of those at the given points, and the intersection of those two perpendicular lines will be the center of the circle. And the distance from that center to either of the two starting points is the radius.
    – Mike Pierce
    Nov 24 at 2:15












  • Ok. Thanks. That's what I had figured. I was hoping there was some trick to getting it without having to manually find the intersection.
    – jd19457
    Nov 24 at 2:19












  • I have to echo @MikePierce’s comment: how are you measuring the number of steps? What is a “step,” anyway? You might, for instance, construct a pair of degenerate conics $Q_1$ and $Q_2$ from the two tangent lines and the secant through the two points and then find the value of $lambda$ that makes the cross term in $(1-lambda)Q_1+lambda Q_2$ vanish. How does that compare to the number of “steps” for the intersecting perpendiculars method?
    – amd
    Nov 24 at 5:10










  • I know this isn't a programming stackexchange, but separate computational steps. This will be in a tight loop, and I want the shortest number of computational steps. I realize some computations are more costly than others, but I just wanted to keep the question strictly math.
    – jd19457
    Nov 24 at 22:15
















0














I've searched and found similar questions, but with less information given, and I was hoping that the additional information would allow for a more streamlined solution.



Given two points, and their tangent angles (not sure if that's the proper term), what's the fewest number of steps to get the center and radius of the circle?



Circle given the information indicated










share|cite|improve this question






















  • What exactly do you mean by fewest number of steps?
    – Mike Pierce
    Nov 24 at 2:14






  • 1




    Having the tangent angles and the points, you basically have two lines that are tangent to the circle. You can construct the lines that are perpendicular to each of those at the given points, and the intersection of those two perpendicular lines will be the center of the circle. And the distance from that center to either of the two starting points is the radius.
    – Mike Pierce
    Nov 24 at 2:15












  • Ok. Thanks. That's what I had figured. I was hoping there was some trick to getting it without having to manually find the intersection.
    – jd19457
    Nov 24 at 2:19












  • I have to echo @MikePierce’s comment: how are you measuring the number of steps? What is a “step,” anyway? You might, for instance, construct a pair of degenerate conics $Q_1$ and $Q_2$ from the two tangent lines and the secant through the two points and then find the value of $lambda$ that makes the cross term in $(1-lambda)Q_1+lambda Q_2$ vanish. How does that compare to the number of “steps” for the intersecting perpendiculars method?
    – amd
    Nov 24 at 5:10










  • I know this isn't a programming stackexchange, but separate computational steps. This will be in a tight loop, and I want the shortest number of computational steps. I realize some computations are more costly than others, but I just wanted to keep the question strictly math.
    – jd19457
    Nov 24 at 22:15














0












0








0







I've searched and found similar questions, but with less information given, and I was hoping that the additional information would allow for a more streamlined solution.



Given two points, and their tangent angles (not sure if that's the proper term), what's the fewest number of steps to get the center and radius of the circle?



Circle given the information indicated










share|cite|improve this question













I've searched and found similar questions, but with less information given, and I was hoping that the additional information would allow for a more streamlined solution.



Given two points, and their tangent angles (not sure if that's the proper term), what's the fewest number of steps to get the center and radius of the circle?



Circle given the information indicated







geometry circle tangent-line






share|cite|improve this question













share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Nov 24 at 2:10









jd19457

1




1












  • What exactly do you mean by fewest number of steps?
    – Mike Pierce
    Nov 24 at 2:14






  • 1




    Having the tangent angles and the points, you basically have two lines that are tangent to the circle. You can construct the lines that are perpendicular to each of those at the given points, and the intersection of those two perpendicular lines will be the center of the circle. And the distance from that center to either of the two starting points is the radius.
    – Mike Pierce
    Nov 24 at 2:15












  • Ok. Thanks. That's what I had figured. I was hoping there was some trick to getting it without having to manually find the intersection.
    – jd19457
    Nov 24 at 2:19












  • I have to echo @MikePierce’s comment: how are you measuring the number of steps? What is a “step,” anyway? You might, for instance, construct a pair of degenerate conics $Q_1$ and $Q_2$ from the two tangent lines and the secant through the two points and then find the value of $lambda$ that makes the cross term in $(1-lambda)Q_1+lambda Q_2$ vanish. How does that compare to the number of “steps” for the intersecting perpendiculars method?
    – amd
    Nov 24 at 5:10










  • I know this isn't a programming stackexchange, but separate computational steps. This will be in a tight loop, and I want the shortest number of computational steps. I realize some computations are more costly than others, but I just wanted to keep the question strictly math.
    – jd19457
    Nov 24 at 22:15


















  • What exactly do you mean by fewest number of steps?
    – Mike Pierce
    Nov 24 at 2:14






  • 1




    Having the tangent angles and the points, you basically have two lines that are tangent to the circle. You can construct the lines that are perpendicular to each of those at the given points, and the intersection of those two perpendicular lines will be the center of the circle. And the distance from that center to either of the two starting points is the radius.
    – Mike Pierce
    Nov 24 at 2:15












  • Ok. Thanks. That's what I had figured. I was hoping there was some trick to getting it without having to manually find the intersection.
    – jd19457
    Nov 24 at 2:19












  • I have to echo @MikePierce’s comment: how are you measuring the number of steps? What is a “step,” anyway? You might, for instance, construct a pair of degenerate conics $Q_1$ and $Q_2$ from the two tangent lines and the secant through the two points and then find the value of $lambda$ that makes the cross term in $(1-lambda)Q_1+lambda Q_2$ vanish. How does that compare to the number of “steps” for the intersecting perpendiculars method?
    – amd
    Nov 24 at 5:10










  • I know this isn't a programming stackexchange, but separate computational steps. This will be in a tight loop, and I want the shortest number of computational steps. I realize some computations are more costly than others, but I just wanted to keep the question strictly math.
    – jd19457
    Nov 24 at 22:15
















What exactly do you mean by fewest number of steps?
– Mike Pierce
Nov 24 at 2:14




What exactly do you mean by fewest number of steps?
– Mike Pierce
Nov 24 at 2:14




1




1




Having the tangent angles and the points, you basically have two lines that are tangent to the circle. You can construct the lines that are perpendicular to each of those at the given points, and the intersection of those two perpendicular lines will be the center of the circle. And the distance from that center to either of the two starting points is the radius.
– Mike Pierce
Nov 24 at 2:15






Having the tangent angles and the points, you basically have two lines that are tangent to the circle. You can construct the lines that are perpendicular to each of those at the given points, and the intersection of those two perpendicular lines will be the center of the circle. And the distance from that center to either of the two starting points is the radius.
– Mike Pierce
Nov 24 at 2:15














Ok. Thanks. That's what I had figured. I was hoping there was some trick to getting it without having to manually find the intersection.
– jd19457
Nov 24 at 2:19






Ok. Thanks. That's what I had figured. I was hoping there was some trick to getting it without having to manually find the intersection.
– jd19457
Nov 24 at 2:19














I have to echo @MikePierce’s comment: how are you measuring the number of steps? What is a “step,” anyway? You might, for instance, construct a pair of degenerate conics $Q_1$ and $Q_2$ from the two tangent lines and the secant through the two points and then find the value of $lambda$ that makes the cross term in $(1-lambda)Q_1+lambda Q_2$ vanish. How does that compare to the number of “steps” for the intersecting perpendiculars method?
– amd
Nov 24 at 5:10




I have to echo @MikePierce’s comment: how are you measuring the number of steps? What is a “step,” anyway? You might, for instance, construct a pair of degenerate conics $Q_1$ and $Q_2$ from the two tangent lines and the secant through the two points and then find the value of $lambda$ that makes the cross term in $(1-lambda)Q_1+lambda Q_2$ vanish. How does that compare to the number of “steps” for the intersecting perpendiculars method?
– amd
Nov 24 at 5:10












I know this isn't a programming stackexchange, but separate computational steps. This will be in a tight loop, and I want the shortest number of computational steps. I realize some computations are more costly than others, but I just wanted to keep the question strictly math.
– jd19457
Nov 24 at 22:15




I know this isn't a programming stackexchange, but separate computational steps. This will be in a tight loop, and I want the shortest number of computational steps. I realize some computations are more costly than others, but I just wanted to keep the question strictly math.
– jd19457
Nov 24 at 22:15















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