How to derive the relation between hyperbolic functions and complex trigonometric ratios? [on hold]












-3












$begingroup$


$$cos(ix)=cosh(x) \
-isin(ix)=sinh(x)$$



I have read that this is derived using Euler's formula $a+bi=re^{itheta}$, but how is this actually done?










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$endgroup$



put on hold as off-topic by user21820, Lord_Farin, user91500, Adrian Keister, José Carlos Santos Jan 16 at 15:18


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


















    -3












    $begingroup$


    $$cos(ix)=cosh(x) \
    -isin(ix)=sinh(x)$$



    I have read that this is derived using Euler's formula $a+bi=re^{itheta}$, but how is this actually done?










    share|cite|improve this question









    $endgroup$



    put on hold as off-topic by user21820, Lord_Farin, user91500, Adrian Keister, José Carlos Santos Jan 16 at 15:18


    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 provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – user21820, Lord_Farin, user91500, Adrian Keister, José Carlos Santos

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
















      -3












      -3








      -3





      $begingroup$


      $$cos(ix)=cosh(x) \
      -isin(ix)=sinh(x)$$



      I have read that this is derived using Euler's formula $a+bi=re^{itheta}$, but how is this actually done?










      share|cite|improve this question









      $endgroup$




      $$cos(ix)=cosh(x) \
      -isin(ix)=sinh(x)$$



      I have read that this is derived using Euler's formula $a+bi=re^{itheta}$, but how is this actually done?







      trigonometry complex-numbers hyperbolic-functions






      share|cite|improve this question













      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked Jan 9 at 19:41









      Pancake_SenpaiPancake_Senpai

      23515




      23515




      put on hold as off-topic by user21820, Lord_Farin, user91500, Adrian Keister, José Carlos Santos Jan 16 at 15:18


      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 provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – user21820, Lord_Farin, user91500, Adrian Keister, José Carlos Santos

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




      put on hold as off-topic by user21820, Lord_Farin, user91500, Adrian Keister, José Carlos Santos Jan 16 at 15:18


      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 provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – user21820, Lord_Farin, user91500, Adrian Keister, José Carlos Santos

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






















          1 Answer
          1






          active

          oldest

          votes


















          1












          $begingroup$

          hint



          Euler formulas are



          $$cos(z)=frac{e^{iz}+e^{-iz}}{2}$$
          and
          $$sin(z)=frac{e^{iz}-e^{-iz}}{2i}$$
          on the other hand



          $$cosh(a)=frac{e^a+e^{-a}}{2}$$
          and
          $$sinh(a)=frac{e^a-e^{-a}}{2}$$



          thus...






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            I don't know why, but I've looked at these equations multiple times and I just didn't 'see' it. It seems painfully obvious now. Thanks.
            $endgroup$
            – Pancake_Senpai
            Jan 9 at 23:38


















          1 Answer
          1






          active

          oldest

          votes








          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          1












          $begingroup$

          hint



          Euler formulas are



          $$cos(z)=frac{e^{iz}+e^{-iz}}{2}$$
          and
          $$sin(z)=frac{e^{iz}-e^{-iz}}{2i}$$
          on the other hand



          $$cosh(a)=frac{e^a+e^{-a}}{2}$$
          and
          $$sinh(a)=frac{e^a-e^{-a}}{2}$$



          thus...






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            I don't know why, but I've looked at these equations multiple times and I just didn't 'see' it. It seems painfully obvious now. Thanks.
            $endgroup$
            – Pancake_Senpai
            Jan 9 at 23:38
















          1












          $begingroup$

          hint



          Euler formulas are



          $$cos(z)=frac{e^{iz}+e^{-iz}}{2}$$
          and
          $$sin(z)=frac{e^{iz}-e^{-iz}}{2i}$$
          on the other hand



          $$cosh(a)=frac{e^a+e^{-a}}{2}$$
          and
          $$sinh(a)=frac{e^a-e^{-a}}{2}$$



          thus...






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            I don't know why, but I've looked at these equations multiple times and I just didn't 'see' it. It seems painfully obvious now. Thanks.
            $endgroup$
            – Pancake_Senpai
            Jan 9 at 23:38














          1












          1








          1





          $begingroup$

          hint



          Euler formulas are



          $$cos(z)=frac{e^{iz}+e^{-iz}}{2}$$
          and
          $$sin(z)=frac{e^{iz}-e^{-iz}}{2i}$$
          on the other hand



          $$cosh(a)=frac{e^a+e^{-a}}{2}$$
          and
          $$sinh(a)=frac{e^a-e^{-a}}{2}$$



          thus...






          share|cite|improve this answer









          $endgroup$



          hint



          Euler formulas are



          $$cos(z)=frac{e^{iz}+e^{-iz}}{2}$$
          and
          $$sin(z)=frac{e^{iz}-e^{-iz}}{2i}$$
          on the other hand



          $$cosh(a)=frac{e^a+e^{-a}}{2}$$
          and
          $$sinh(a)=frac{e^a-e^{-a}}{2}$$



          thus...







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Jan 9 at 20:12









          hamam_Abdallahhamam_Abdallah

          38k21634




          38k21634












          • $begingroup$
            I don't know why, but I've looked at these equations multiple times and I just didn't 'see' it. It seems painfully obvious now. Thanks.
            $endgroup$
            – Pancake_Senpai
            Jan 9 at 23:38


















          • $begingroup$
            I don't know why, but I've looked at these equations multiple times and I just didn't 'see' it. It seems painfully obvious now. Thanks.
            $endgroup$
            – Pancake_Senpai
            Jan 9 at 23:38
















          $begingroup$
          I don't know why, but I've looked at these equations multiple times and I just didn't 'see' it. It seems painfully obvious now. Thanks.
          $endgroup$
          – Pancake_Senpai
          Jan 9 at 23:38




          $begingroup$
          I don't know why, but I've looked at these equations multiple times and I just didn't 'see' it. It seems painfully obvious now. Thanks.
          $endgroup$
          – Pancake_Senpai
          Jan 9 at 23:38



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