Editing Latitude (section)

===Geocentric latitude===
{{see also|#Geodetic and geocentric latitudes}}
[[File:Geocentric coords 03.svg|right|thumb|upright=1.15|The definition of geodetic latitude ({{mvar|ϕ}}) and geocentric latitude ({{mvar|θ}})]]
The '''geocentric latitude''' is the angle between the equatorial plane and the radius from the centre to a point of interest.

When the point is on the surface of the ellipsoid, the relation between the geocentric latitude ({{mvar|θ}}) and the geodetic latitude ({{mvar|ϕ}}) is:
:<math>\theta(\phi) = \tan^{-1}\left(\left(1 - e^2\right)\tan\phi\right) = \tan^{-1}\left((1 - f)^2\tan\phi\right)\,.</math>
For points not on the surface of the ellipsoid, the relationship involves additionally the [[ellipsoidal height]] ''h'':
: <math>\theta(\phi,h) = \tan^{-1}\left( \frac{N(1 - f)^2 + h}{ N + h}\tan\phi \right)</math>

where {{mvar|N}} is the prime vertical radius of curvature. The geodetic and geocentric latitudes are equal at the equator and at the poles but at other latitudes they differ by a few minutes of arc. Taking the value of the squared eccentricity as 0.0067 (it depends on the choice of ellipsoid) the maximum difference of <math>\phi{-}\theta</math> may be shown to be about 11.5 minutes of arc at a geodetic latitude of approximately 45°&nbsp;6′.{{efn|An elementary calculation involves differentiation to find the maximum difference of the geodetic and geocentric latitudes.
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