# Kepler prediction problem, fundamentals of astrodynamics

I needed help with problem 4.3 of Fundamentals of Astrodynamics by Roger R. Bate, Donald D. Mueller, Jerry E. White (dover, archive.org)

Given that $$r_0 = (I+j)$$ and $$v_0 = 2k$$ find $$r$$ and $$v$$ for difference in true anomaly 60°...

I tried this problem but had no way of finding the universal variable X for the first iteration, if anyone could help me with this it would be appreciated.

Here is a screen shot of the question in response to comments, from books.google.com.in:

• @DavidHammen the difference in true anomaly part is the angle travelled in the elliptical orbit by the body is 60° – user36620 Jun 14 '20 at 7:44
• @JCRM I was able to solve the other problems but the main difference was chapter 4 teaches you to predict for the time given but it's not clear when the only given is the angular travel of the body in the orbit – user36620 Jun 14 '20 at 11:53
• you'll need to calculate the time first then – user20636 Jun 14 '20 at 13:02
• Apparently I was taking the wrong formula of eccentric anomaly for hyperbolic orbits which was the error.....I got the answer finally – user36620 Jun 14 '20 at 14:22
• If you figured it out on your own, you can provide an answer here to help out others in the future. It's perfectly fine to answer your own question. – called2voyage Jun 15 '20 at 13:45