I am trying to work out the length of the Rsv, but I dont understand how to go about this. If the length R is known and the angle EL is known how do I go about solving for this length. I was given some formulas but again I feel there is too many unknowns

I have thought about trigonometry and sine and cosine, but still am unsure. Any help would be great. The image is shown below for the problem enter image description here

  • $\begingroup$ SE Space Exploration might be able to help with this. $\endgroup$
    – Fred
    Mar 26, 2022 at 16:14
  • 1
    $\begingroup$ 2 sides and the included angle: law of cosine. $\endgroup$
    – JohnHoltz
    Mar 26, 2022 at 18:31

1 Answer 1


The Law of cosines can be used to find the length of the third side of a triangle when two sides and the included angle are known.

$$R_{SV}^2 = R^2+R_E^2 -2R_{SV}R_E\cos(90+\theta_{EL})$$


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