How to get my function from these dsolve results

[Dwightun]

TL;DR

I got the solution by dsolve? but don't understand how to get my function from it

Hi!
I'm trying to solve ODE system with 2 equations
Here is a result from dsolve. How can i get R(t) out of it
And how to substitute initial conditions in it?

 

[Ssnow]

Your system seems also non linear in $Z(t)$ ... , you can try to solve the differential equation given in $b(a)$ using copy and past on Maple ...
Ssnow