If the Sun's observed altitude is 54°30', what is the zenith distance?
Official USCG Answer & Rule Citation
Correct Answer: Option D — 35°30'
Zenith distance is fundamentally defined in celestial navigation as the complement of the observed altitude, calculated by subtracting Ho from 90 degrees. Subtracting 54°30' from 89°60' directly produces the remainder of 35°30'.
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