- #1
whatisreality
- 290
- 1
1. Homework Statement
It's to do with mirages, but I don't think the physics context is too important. It's also possible that the solution doesn't involve differential equations, and my method is completely wrong. I've been given that:
##A = \frac{n(1+ay)}{ sqrt(1+(y')^2)}##
where y' is dy/dx. I have to show that
##y = -\frac{1}{a} + \frac{A}{na}## cosh( ##\frac{na}{A}##(x-x0))
A, n and a are real constants.
Homework Equations
The Attempt at a Solution
I tried rearranging it to get dy/dx = ... , by multiplying by the denominator then dividing by A, squaring both sides, subtracting 1 and then square rooting. I ended up with:
##y'=\sqrt{\frac{n^2 (1+ay)^2}{A^2} -1}##
And that's separable. So
##dx = \frac{1}{\sqrt{\frac{n^2 (1+ay)^2}{A^2} -1}}dy##
And then if I integrate both sides by doing substitutions like u =1+ay, I get ln of something. Nowhere near the show that result.
Checked the rearrangement so many times. What did I do?