Question 1210336
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(b) The points X(70°S, 60°E) and Y(7°S, 60°E) lies on the surface of the earth.
(i) Illustrate the information in a diagram.
(ii) Find the distance between X and Y along the meridian.
[Take л = 22/7 and R = 6,400 km]
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        Calculations in the post by @greenestamps, giving the answer of 3520 km,  are erroneous.



From the school, we know that the Earth circumference along the equator 
is about 40,000 kilometers.


In this problem, we consider the Earth as spherical; so, its circumference 
in any meridional section is the same 40,000 km.


Hence, under this assumption, the distance from the South pole to the North pole 
along any meridian is half of 40,000 km, i.e. 20,000 km.


In this problem, the distance between the given points is 70° - 7° = 63°, measured as the difference of altitudes.


It is about one third of 180°, which represents the distance between the poles, expressed in degrees.


So, we can expect, that the distance between the given points is at least one third of 20,000 km.
i.e., at least  6666 km.



If you want to derive the value using the formula, you should write


          {{{((70-7)/360)*(2*pi*R)}}} = {{{((70-7)/180)*(22/7)*6400}}} = {{{(63/180)*(22/7)*6400}}} = {{{(7/20)*(22/7)*6400}}} = {{{(22/20)*6400}}} = 22*320 = 7040 kilometers.


It is the precise answer (under the given values and assumptions), 
and it is consistent with my crude evaluation above.


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Solved, with explanations.