1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Calculus please help me solve this simple problem (I forgot how to): arcsin(4/5) = ?

  1. Jul 20, 2010 #1
    1. The problem statement, all variables and given/known data

    how do I solve this

    arcsin(4/5)

    note that I am not looking for about 53 degrees

    I believe I'm suppose to solve euler's formula for x

    i.e.
    sin (x) = (e^(ix) - e^(-ix))/(2i)
    where x is in radians
    hence I would do something like this

    sin (x) = (e^(ix) - e^(-ix))/(2i) = 4/5

    (e^(ix) - e^(-ix))/(2i) = 4/5
    solve the equation above for x

    this is were I need help if somebody could just show me quickly how to do this that would be great!!!

    If I remeber correctly I need to use cis(x) or something right?


    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Jul 20, 2010 #2
    Re: Calculus please help me solve this simple problem (I forgot how to): arcsin(4/5)

    ok now this is an algebra 2 problem... I have goten far down to hear

    e^(ix) = (4i +/- 3)/5

    now how do I solve for x I feel really stupid now as this is algebra 2...

    can't use natural log right or the common log as

    ln( e^(ix) )
    does not equal ix

    so what do I do?
     
  4. Jul 20, 2010 #3
    Re: Calculus please help me solve this simple problem (I forgot how to): arcsin(4/5)

    Wait apparently I'm suppose to do something involving

    log(z) = ln|z| + i arg(z) for complex numbers z

    or something correct?
     
  5. Jul 21, 2010 #4

    hunt_mat

    User Avatar
    Homework Helper

    Re: Calculus please help me solve this simple problem (I forgot how to): arcsin(4/5)

    Try it and see.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Calculus please help me solve this simple problem (I forgot how to): arcsin(4/5) = ?
Loading...