- #1
Leo Liu
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- TL;DR Summary
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My physics textbook does the approximation that $$r=\frac{r_0}{1-\frac{A}{r_0}\sin\theta}\approx r_0\left( 1+\frac A r_0\sin\theta\right)$$ when ##A/r_0 \ll 1##. Can someone please explain how it is done?