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56.2: Radius of the Earth

Last updated

Feb 3, 2024
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- 56.1: Introduction to Geodesy
- 56.3: The Cosine Formula

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There is a useful formula that gives the radius of the Earth $R$ at any latitude $\phi$ :

$R(\phi)=\sqrt{\frac{\left(a^{2} \cos \phi\right)^{2}+\left(b^{2} \sin \phi\right)^{2}}{(a \cos \phi)^{2}+(b \sin \phi)^{2}}}$

where, as before, the equatorial radius $a=6378.1370 \mathrm{~km}$ , and the polar radius $b=a(1-f)=6356.7523142$ km (WGS 84).

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