Hover or tap underlined Spanish terms to see their translation and exam tip.
Calcular la distancia ortodrómica entre Vigo (42º 14,1' N, 008º 43,6' W) y Río de Janeiro (22º 54,4' S, 043º 11,8' W).Calculate the great-circle distance between Vigo (42º 14.1' N, 008º 43.6' W) and Rio de Janeiro (22º 54.4' S, 043º 11.8' W).
Show the answer
Correct answer: c) 4350'
Why it is correct
With ΔL = 34º 28.2′ and latitudes in opposite hemispheres, the sine product subtracts: cos D = −sin(42º 14.1′) sin(22º 54.4′) + cos(42º 14.1′) cos(22º 54.4′) cos(34º 28.2′) = 0.29998. Thus D = 72.504º, and times 60 that is 4350 miles.
Why the others are not
- a) Subtracts the latitudes instead of applying the spherical formula.
- b) Adds the sine term as if both points lay in the same hemisphere.
- d) Adds the longitudes instead of subtracting them when both are west.
How to work it out in the exam
- Opposite hemispheres: the sin l1 sin l2 term takes a negative sign.
Where this question comes from
- Junta de Andalucía · 2020 · Convocatoria de e · CY Módulo de navegación · question 18 Official paper · Official answer key
Pending instructor review. Machine translation, not reviewed.