Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Find the value of ?

  1. Apr 5, 2008 #1
    1. The problem statement, all variables and given/known data

    Find the value of sin inverse (2 ) ?

    2. Relevant equations

    3. The attempt at a solution

    This was a question in my final exam & i had no clue about it
  2. jcsd
  3. Apr 5, 2008 #2
    is it a real value? what is the domain of the ArcSin function?
  4. Apr 5, 2008 #3
    No extra information was given
  5. Apr 5, 2008 #4

    Gib Z

    User Avatar
    Homework Helper

    Suppose such a value, k, exists, so that [tex]\arcsin 2 = k[/tex]. Then taking sines of both sides, [tex]sin (k) = 2[/tex]. However, the sine function is bounded between -1 and 1 for all real numbers. Hence there is no real solution.
  6. Apr 5, 2008 #5


    User Avatar
    Science Advisor
    Homework Helper

    … hyperbolic sines … !

    Hi mkbh_10! Hope you passed! :smile:

    Hint: cosh ix = cosx, and sinh ix = isinx.

    (that's why sinh is called the hyperbolic sin!)

    So sin(x + iy) = sinx cos iy + cosx sin iy = sinx coshy - i cosx sinhy;

    so you needed cosx = 0, and … ? :smile:
  7. Apr 5, 2008 #6

    But there is no hyperbolic sine function in the question ?

    I am studying in DU (Delhi University ) so results will only be out in mid July . I will definitely pass but i want top marks which i will not be getting in this paper coz of my silly mistakes .
  8. Apr 5, 2008 #7


    User Avatar
    Science Advisor

    What course is this for? That's important. If you are studying complex numbers in the course, then there is a solution, if not, there is no solution.

    And just because there is no "hyperbolic sine" in the problem doesn't mean you can't use one to solve it.
  9. Apr 5, 2008 #8
    i have not found it anywhere in my course , thats why i am asking , i didn't study this type of question neither did our teacher taught nor does the book has this type of questions
  10. Apr 5, 2008 #9
    i have studied complex numbers but i have no clue about it
  11. Apr 5, 2008 #10


    User Avatar
    Science Advisor
    Homework Helper

    … really unfair … !

    That's really unfair! :mad:

    (even if you've done things like log(-1) and log(i), sin(ix) isn't obvious, and should have been pointed out to you, IMO)

    (Check the official syllabus, to see if it's on it … if it's not, complain about the exam … if it is, check with your fellow students, and make a joint request for credit for that question … will your student union help you with that?)

    (btw, sin (π/2 - isinh^(-1)2) = 2)
  12. Apr 5, 2008 #11
    this is india, nothing happens at student level , & there are 30-40 clgs in DU that have this course & who knows what teacher teaches in a particular topic
  13. Apr 5, 2008 #12
    share your pain bro.. share your pain.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook