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Simultaneous Equations

  1. Sep 9, 2005 #1
    Can anyone analytically solve these 2 simultaneous equations for c & d, where a and b are known?

    a = sin(c) * cosh(d)
    b = cos(c) * sinh(d)

    I can eliminate 'c' to get:

    (sinh d)^2 = b^2 + (a^2)*(tanh d)^2

    but this doesn't seem to make life any easier.
  2. jcsd
  3. Sep 9, 2005 #2
    Arggghhhh... I've just this second seen how to do it: write (tanh d)^2 as 1/(cosh d)^2 and then (cosh d)^2 as 1 + (sinh d)^2, multiply though by (sinh d)^2, and solve as a quadratic.

    I have an annoying habit of asking for help and then doing it myself a few minutes later... sorry.
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