Find Lambda from this arbitrary triangle

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bugatti79
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Folks,

I am puzzled how one obtains equation 3.2.31 based on the schematic as attached! Can you help?
Is there an online source I can refer to to learn how to obtain angles and magnitudes of complex schematics?

Thanks
 

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I am still working on this one...
However, I feel like the secret will be in manipulating the equation you have.
Edited*
##\frac{\sin \psi }{ m - \cos \psi } = \frac{\sin( \pi - \psi) }{ a/p +\cos( \pi - \psi) } = \frac{p\sin( \pi - \psi) }{ a + p \cos ( \pi - \psi) }##
This should help you visualize the triangle you should be working with for ##\tan \lambda##.
 
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Hi, thanks...
This is as far as I got...see attached...
 

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That looks good. You extension works to give you a solution for lambda. But it doesn't help get to that tan lambda formula you were looking for.

Try to extend the side length a to make a right triangle with hypotenuse of p. Use sin and cos to determine the side lengths.
Then you can directly get the formula for tangent using the opposite/adjacent of the appropriate right trangle which includes angle lambda.
 
Hi RUber,

I have it. The extended segment of "a" which forms a right angled triangle with P is Pcos(pi-psi). The tan of lambda is obvious. Thank you very much.
I have learned a new way of tacking triangles!
 
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