Asymptotic approximation/expansion for arccosine function?











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Trying to find a 3-term asymptotic expansion for $z=cos^{-1}(x)$, as $xrightarrow1^-$. Found a lot of examples online for inverse tangent, cosine, etc. but have yet to find any guidance on the inverse cosine function. Any help would be greatly appreciated.










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    Trying to find a 3-term asymptotic expansion for $z=cos^{-1}(x)$, as $xrightarrow1^-$. Found a lot of examples online for inverse tangent, cosine, etc. but have yet to find any guidance on the inverse cosine function. Any help would be greatly appreciated.










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      down vote

      favorite









      up vote
      0
      down vote

      favorite











      Trying to find a 3-term asymptotic expansion for $z=cos^{-1}(x)$, as $xrightarrow1^-$. Found a lot of examples online for inverse tangent, cosine, etc. but have yet to find any guidance on the inverse cosine function. Any help would be greatly appreciated.










      share|cite|improve this question













      Trying to find a 3-term asymptotic expansion for $z=cos^{-1}(x)$, as $xrightarrow1^-$. Found a lot of examples online for inverse tangent, cosine, etc. but have yet to find any guidance on the inverse cosine function. Any help would be greatly appreciated.







      asymptotics trigonometric-series






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      asked Nov 15 at 20:17









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          This is equivalent to the expansion of $arccos(1-t)$ at $t=0^{+}$.



          Ask Wolfram Alpha Series[Arccos[1-t)],{t,0,3}]and re-substitute $t=1-x$ in the result
          $$arccos(1-t) =sqrt{2} sqrt{t} + frac{t^{3/2}}{6 sqrt{2}} + frac{3t^{5/2}}{80 sqrt{2}}
          + frac{5 t^{7/2}}{448 sqrt{2}} + O(t^{9/2})$$

          or see 1.



          Yet another approach would be do use the trigonometric identity from
          2 and get
          $$arccos(1-t) = 2arcsinleft(sqrt{t/2}right),$$
          Then use the expansion of $arcsin.$






          share|cite|improve this answer























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            1 Answer
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            This is equivalent to the expansion of $arccos(1-t)$ at $t=0^{+}$.



            Ask Wolfram Alpha Series[Arccos[1-t)],{t,0,3}]and re-substitute $t=1-x$ in the result
            $$arccos(1-t) =sqrt{2} sqrt{t} + frac{t^{3/2}}{6 sqrt{2}} + frac{3t^{5/2}}{80 sqrt{2}}
            + frac{5 t^{7/2}}{448 sqrt{2}} + O(t^{9/2})$$

            or see 1.



            Yet another approach would be do use the trigonometric identity from
            2 and get
            $$arccos(1-t) = 2arcsinleft(sqrt{t/2}right),$$
            Then use the expansion of $arcsin.$






            share|cite|improve this answer



























              up vote
              1
              down vote













              This is equivalent to the expansion of $arccos(1-t)$ at $t=0^{+}$.



              Ask Wolfram Alpha Series[Arccos[1-t)],{t,0,3}]and re-substitute $t=1-x$ in the result
              $$arccos(1-t) =sqrt{2} sqrt{t} + frac{t^{3/2}}{6 sqrt{2}} + frac{3t^{5/2}}{80 sqrt{2}}
              + frac{5 t^{7/2}}{448 sqrt{2}} + O(t^{9/2})$$

              or see 1.



              Yet another approach would be do use the trigonometric identity from
              2 and get
              $$arccos(1-t) = 2arcsinleft(sqrt{t/2}right),$$
              Then use the expansion of $arcsin.$






              share|cite|improve this answer

























                up vote
                1
                down vote










                up vote
                1
                down vote









                This is equivalent to the expansion of $arccos(1-t)$ at $t=0^{+}$.



                Ask Wolfram Alpha Series[Arccos[1-t)],{t,0,3}]and re-substitute $t=1-x$ in the result
                $$arccos(1-t) =sqrt{2} sqrt{t} + frac{t^{3/2}}{6 sqrt{2}} + frac{3t^{5/2}}{80 sqrt{2}}
                + frac{5 t^{7/2}}{448 sqrt{2}} + O(t^{9/2})$$

                or see 1.



                Yet another approach would be do use the trigonometric identity from
                2 and get
                $$arccos(1-t) = 2arcsinleft(sqrt{t/2}right),$$
                Then use the expansion of $arcsin.$






                share|cite|improve this answer














                This is equivalent to the expansion of $arccos(1-t)$ at $t=0^{+}$.



                Ask Wolfram Alpha Series[Arccos[1-t)],{t,0,3}]and re-substitute $t=1-x$ in the result
                $$arccos(1-t) =sqrt{2} sqrt{t} + frac{t^{3/2}}{6 sqrt{2}} + frac{3t^{5/2}}{80 sqrt{2}}
                + frac{5 t^{7/2}}{448 sqrt{2}} + O(t^{9/2})$$

                or see 1.



                Yet another approach would be do use the trigonometric identity from
                2 and get
                $$arccos(1-t) = 2arcsinleft(sqrt{t/2}right),$$
                Then use the expansion of $arcsin.$







                share|cite|improve this answer














                share|cite|improve this answer



                share|cite|improve this answer








                edited Nov 15 at 22:06

























                answered Nov 15 at 21:01









                gammatester

                16.3k21630




                16.3k21630






























                     

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