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- Problem Statement
- Find the path followed by a light ray if the index of refraction (in polar coordinates) is proportional to r^-2.

- Relevant Equations
- ∫nds

This is an example from a textbook. They show the following:

∫nds = ∫r

How do you obtain the expression for ds?

∫nds = ∫r

^{-2}*ds = ∫r^{-2}*√((dr)^{2}+r^{2}*(dθ)^{2})How do you obtain the expression for ds?