# Homework Help: Classical ellipsoidal scattering Impact parameter

1. Dec 9, 2017

### insanelover11

1. The problem statement, all variables and given/known data
(x^2 + y^2)/a^2 + z^2/c^2 = 1

2. Relevant equations

3. The attempt at a solution

b(θ) = R / (f^2 * tan^2(θ/2) + 1)^0.5
I can't understand how to calculate this.

My attempt :
(x^2 + y^2)/a^2 + z^2/c^2 = 1 from this.

b^2 + z^2/f^2 = a^2 , f = c/a, z = b*cot(∅)

b^2 *[ 1 + {1/f*tan(∅)}^2 ] = a^2

could you give a hand?...

2. Dec 9, 2017

### Staff: Mentor

Hello, it would be helpful, if you explained what is expected to be done. E.g. there is no "b" nor a "$\theta$" in the problem description. Also you should use more parentheses in case of a linear notation of quotients. Of course it would be far better, if you could use LaTeX code. For a brief introduction see: https://www.physicsforums.com/help/latexhelp/
(It's quite easy to make formulas a lot more readable.)