The function $f(x)=arcsin(asinh(sin(x)))$












1












$begingroup$


While playing around with Desmos, I came across the function $$f(x)=arcsin(asinh(sin(x)))$$
where $ainmathbb{R}$ is a constant (whose value changes the function drastically; if you see the graph, you will understand).



So I came up with the following question (which I don't know how to extract an answer other than an approximation):




We have the function $f:Atomathbb{R}$, given by $$f(x)=arcsin(asinh(sin(x)))$$ with $ain B=[-m,m]subsetmathbb{R}$, and $minmathbb{R}$.



What is the biggest value of $m$ such that $f$ is continuous for every $x=(2k+1)dfracpi{2}$ (with $k$ an integer), and thus $A=mathbb{R}$? Is the number $m$ rational or irrational?



(A little hint: $mapprox 0.850918$.)











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    1












    $begingroup$


    While playing around with Desmos, I came across the function $$f(x)=arcsin(asinh(sin(x)))$$
    where $ainmathbb{R}$ is a constant (whose value changes the function drastically; if you see the graph, you will understand).



    So I came up with the following question (which I don't know how to extract an answer other than an approximation):




    We have the function $f:Atomathbb{R}$, given by $$f(x)=arcsin(asinh(sin(x)))$$ with $ain B=[-m,m]subsetmathbb{R}$, and $minmathbb{R}$.



    What is the biggest value of $m$ such that $f$ is continuous for every $x=(2k+1)dfracpi{2}$ (with $k$ an integer), and thus $A=mathbb{R}$? Is the number $m$ rational or irrational?



    (A little hint: $mapprox 0.850918$.)











    share|cite|improve this question











    $endgroup$















      1












      1








      1


      0



      $begingroup$


      While playing around with Desmos, I came across the function $$f(x)=arcsin(asinh(sin(x)))$$
      where $ainmathbb{R}$ is a constant (whose value changes the function drastically; if you see the graph, you will understand).



      So I came up with the following question (which I don't know how to extract an answer other than an approximation):




      We have the function $f:Atomathbb{R}$, given by $$f(x)=arcsin(asinh(sin(x)))$$ with $ain B=[-m,m]subsetmathbb{R}$, and $minmathbb{R}$.



      What is the biggest value of $m$ such that $f$ is continuous for every $x=(2k+1)dfracpi{2}$ (with $k$ an integer), and thus $A=mathbb{R}$? Is the number $m$ rational or irrational?



      (A little hint: $mapprox 0.850918$.)











      share|cite|improve this question











      $endgroup$




      While playing around with Desmos, I came across the function $$f(x)=arcsin(asinh(sin(x)))$$
      where $ainmathbb{R}$ is a constant (whose value changes the function drastically; if you see the graph, you will understand).



      So I came up with the following question (which I don't know how to extract an answer other than an approximation):




      We have the function $f:Atomathbb{R}$, given by $$f(x)=arcsin(asinh(sin(x)))$$ with $ain B=[-m,m]subsetmathbb{R}$, and $minmathbb{R}$.



      What is the biggest value of $m$ such that $f$ is continuous for every $x=(2k+1)dfracpi{2}$ (with $k$ an integer), and thus $A=mathbb{R}$? Is the number $m$ rational or irrational?



      (A little hint: $mapprox 0.850918$.)








      functions trigonometry recreational-mathematics






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      share|cite|improve this question













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      edited Jan 6 at 23:20









      Blue

      48k870153




      48k870153










      asked Jan 6 at 22:47









      Negafilms OriginsNegafilms Origins

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          1 Answer
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          $begingroup$

          The exact value of $m$ must be such that:
          $$
          msinh(1)=1
          $$

          and thus:
          $$
          m=frac{1}{sinh(1)}approx 0.8509181282
          $$

          which I would suspect is irrational. For greater values of $m$ we will have $msinh(sin(x))$ outside the domain $[-1,1]$ of $arcsin$ which is why the graph breaks.






          share|cite|improve this answer









          $endgroup$









          • 3




            $begingroup$
            By L-W theorem, $e^1$, $e^{-1}$, and $e^0$ are linearly independent over the algebraic numbers, so in particular $frac{e^1+e^{-1}}{2}=sinh 1$ cannot be rational.
            $endgroup$
            – vadim123
            Jan 6 at 23:15













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          1 Answer
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          active

          oldest

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          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          2












          $begingroup$

          The exact value of $m$ must be such that:
          $$
          msinh(1)=1
          $$

          and thus:
          $$
          m=frac{1}{sinh(1)}approx 0.8509181282
          $$

          which I would suspect is irrational. For greater values of $m$ we will have $msinh(sin(x))$ outside the domain $[-1,1]$ of $arcsin$ which is why the graph breaks.






          share|cite|improve this answer









          $endgroup$









          • 3




            $begingroup$
            By L-W theorem, $e^1$, $e^{-1}$, and $e^0$ are linearly independent over the algebraic numbers, so in particular $frac{e^1+e^{-1}}{2}=sinh 1$ cannot be rational.
            $endgroup$
            – vadim123
            Jan 6 at 23:15


















          2












          $begingroup$

          The exact value of $m$ must be such that:
          $$
          msinh(1)=1
          $$

          and thus:
          $$
          m=frac{1}{sinh(1)}approx 0.8509181282
          $$

          which I would suspect is irrational. For greater values of $m$ we will have $msinh(sin(x))$ outside the domain $[-1,1]$ of $arcsin$ which is why the graph breaks.






          share|cite|improve this answer









          $endgroup$









          • 3




            $begingroup$
            By L-W theorem, $e^1$, $e^{-1}$, and $e^0$ are linearly independent over the algebraic numbers, so in particular $frac{e^1+e^{-1}}{2}=sinh 1$ cannot be rational.
            $endgroup$
            – vadim123
            Jan 6 at 23:15
















          2












          2








          2





          $begingroup$

          The exact value of $m$ must be such that:
          $$
          msinh(1)=1
          $$

          and thus:
          $$
          m=frac{1}{sinh(1)}approx 0.8509181282
          $$

          which I would suspect is irrational. For greater values of $m$ we will have $msinh(sin(x))$ outside the domain $[-1,1]$ of $arcsin$ which is why the graph breaks.






          share|cite|improve this answer









          $endgroup$



          The exact value of $m$ must be such that:
          $$
          msinh(1)=1
          $$

          and thus:
          $$
          m=frac{1}{sinh(1)}approx 0.8509181282
          $$

          which I would suspect is irrational. For greater values of $m$ we will have $msinh(sin(x))$ outside the domain $[-1,1]$ of $arcsin$ which is why the graph breaks.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Jan 6 at 23:07









          StringString

          13.7k32756




          13.7k32756








          • 3




            $begingroup$
            By L-W theorem, $e^1$, $e^{-1}$, and $e^0$ are linearly independent over the algebraic numbers, so in particular $frac{e^1+e^{-1}}{2}=sinh 1$ cannot be rational.
            $endgroup$
            – vadim123
            Jan 6 at 23:15
















          • 3




            $begingroup$
            By L-W theorem, $e^1$, $e^{-1}$, and $e^0$ are linearly independent over the algebraic numbers, so in particular $frac{e^1+e^{-1}}{2}=sinh 1$ cannot be rational.
            $endgroup$
            – vadim123
            Jan 6 at 23:15










          3




          3




          $begingroup$
          By L-W theorem, $e^1$, $e^{-1}$, and $e^0$ are linearly independent over the algebraic numbers, so in particular $frac{e^1+e^{-1}}{2}=sinh 1$ cannot be rational.
          $endgroup$
          – vadim123
          Jan 6 at 23:15






          $begingroup$
          By L-W theorem, $e^1$, $e^{-1}$, and $e^0$ are linearly independent over the algebraic numbers, so in particular $frac{e^1+e^{-1}}{2}=sinh 1$ cannot be rational.
          $endgroup$
          – vadim123
          Jan 6 at 23:15




















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