Why is $cos(i)-i sin(i)=e$? [duplicate]












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  • Why Euler's formula is true? [duplicate]

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When I was typing $cos(i)-i sin(i)$ into the calculator, I found out that it is equal to e (Euler's Constant). I was amazed by that "discovery" so I checked in on the internet and there was no results. Someone please explain the connection of imaginary numbers and Euler's Constant.










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marked as duplicate by lab bhattacharjee, Brahadeesh, Leucippus, Shailesh, Cesareo Dec 13 '18 at 8:52


This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.























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    This question already has an answer here:




    • Why Euler's formula is true? [duplicate]

      1 answer




    When I was typing $cos(i)-i sin(i)$ into the calculator, I found out that it is equal to e (Euler's Constant). I was amazed by that "discovery" so I checked in on the internet and there was no results. Someone please explain the connection of imaginary numbers and Euler's Constant.










    share|cite|improve this question











    $endgroup$



    marked as duplicate by lab bhattacharjee, Brahadeesh, Leucippus, Shailesh, Cesareo Dec 13 '18 at 8:52


    This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.





















      1












      1








      1





      $begingroup$



      This question already has an answer here:




      • Why Euler's formula is true? [duplicate]

        1 answer




      When I was typing $cos(i)-i sin(i)$ into the calculator, I found out that it is equal to e (Euler's Constant). I was amazed by that "discovery" so I checked in on the internet and there was no results. Someone please explain the connection of imaginary numbers and Euler's Constant.










      share|cite|improve this question











      $endgroup$





      This question already has an answer here:




      • Why Euler's formula is true? [duplicate]

        1 answer




      When I was typing $cos(i)-i sin(i)$ into the calculator, I found out that it is equal to e (Euler's Constant). I was amazed by that "discovery" so I checked in on the internet and there was no results. Someone please explain the connection of imaginary numbers and Euler's Constant.





      This question already has an answer here:




      • Why Euler's formula is true? [duplicate]

        1 answer








      complex-numbers eulers-constant






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      edited Dec 13 '18 at 8:38









      Martin Sleziak

      44.7k10119272




      44.7k10119272










      asked Dec 12 '18 at 12:25









      Mr. MathsMr. Maths

      64




      64




      marked as duplicate by lab bhattacharjee, Brahadeesh, Leucippus, Shailesh, Cesareo Dec 13 '18 at 8:52


      This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.









      marked as duplicate by lab bhattacharjee, Brahadeesh, Leucippus, Shailesh, Cesareo Dec 13 '18 at 8:52


      This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
























          1 Answer
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          $begingroup$

          We have $e^{iz}=cos z+i sin z$ for all $z in mathbb C$. This can easily seen with power series. Now plug in $z=-i$.






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            1 Answer
            1






            active

            oldest

            votes








            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            5












            $begingroup$

            We have $e^{iz}=cos z+i sin z$ for all $z in mathbb C$. This can easily seen with power series. Now plug in $z=-i$.






            share|cite|improve this answer









            $endgroup$


















              5












              $begingroup$

              We have $e^{iz}=cos z+i sin z$ for all $z in mathbb C$. This can easily seen with power series. Now plug in $z=-i$.






              share|cite|improve this answer









              $endgroup$
















                5












                5








                5





                $begingroup$

                We have $e^{iz}=cos z+i sin z$ for all $z in mathbb C$. This can easily seen with power series. Now plug in $z=-i$.






                share|cite|improve this answer









                $endgroup$



                We have $e^{iz}=cos z+i sin z$ for all $z in mathbb C$. This can easily seen with power series. Now plug in $z=-i$.







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Dec 12 '18 at 12:28









                FredFred

                46.9k1848




                46.9k1848















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