[Math] The geometric meaning of certain mappings written in cylindrical or spherical coordinates

calculuscoordinate systemsspherical coordinates

What is the geometric meaning of the following mappings, that are written in cylindrical coordinates?

The mappings are: $$(r, \theta, z) \rightarrow(r, \theta , -z) \\ (r, \theta , z) \rightarrow (r, \theta +\pi , -z)$$

And what is the geometric meaning of the following mappings, that are written in spherical coordinates?

The mappings are: $$(\rho , \theta , \phi) \rightarrow (\rho , \theta +\pi , \phi) \\ (\rho , \theta , \phi) \rightarrow (\rho , \theta , \pi-\phi)$$

Best Answer

It looks to me like the question includes two pairs of mappings. Nonetheless:

Hint One concrete way to see this is to write each of the coordinate triples involved in rectangular coordinates using the usual transformation rules. (Alternately, one can meditate a bit on the geometric meaning of each of the coordinates $r, \theta, z, \rho, \phi$. In fact, I think it would be instructive to do this concretely as above, and then "meditatively".)

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