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## Main Question or Discussion Point

I was reading on planetary motion and have gotten hung up on a "rearrangement of terms" that the author skimmed over. It reads that:

r=e(k+rcos(θ))=(ek)/(1-ecos(θ))

It's been a while since I've been in a math class: I just can't follow how to get from a to b. Is there anyone who can walk me through this like I'm twelve?

Thanks!

r=e(k+rcos(θ))=(ek)/(1-ecos(θ))

It's been a while since I've been in a math class: I just can't follow how to get from a to b. Is there anyone who can walk me through this like I'm twelve?

Thanks!