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

  • Thread starter GreenPrint
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  • #1
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Homework Statement



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?


Homework Equations





The Attempt at a Solution

 

Answers and Replies

  • #2
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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?
 
  • #3
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Wait apparently I'm suppose to do something involving

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

or something correct?
 
  • #4
hunt_mat
Homework Helper
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Try it and see.
 

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