I've uploaded a bigger version of the image, split in two figures.
Hello,
may someone be so kind to explain how to arrive, step by step, from equation 23 to 28?
Most of all I would like to understand the approximation with delta: if I substitute eq26 in 25 I get a different result (e.g. delta^3 terms).
See the attached image.
Thank you very much.
PS
eq24 may be taken as it is, I mean, phi is simply "(A D Cs / x') - (c D Cs/2)"
I can update the problem since there is some progress:
I have the following equation
[eq1]
eq1 is approximated with [eq2]
Where does this approximation come from and why is ?
Thank you very much.
I've found the solution !!
Premise the result was not [tex]\delta=b/3[\tex] but [tex]\delta=-b/2[\tex]
we have two equations, basically:
and with a small δ
Writing those two equations in a system, we have that the δ that satisfy both equations is a δ that satisfy this 3rd order equation:
ignoring third order and second order terms in δ we have simply
so the result