Geometry of the Earth HELP (1 Viewer)

[mrh94]

When finding the distance between two points, how do you tell which part of the coordinates you use?

e.g (12S, 130E) and (43N, 147E)
OR ( 43N,79W) (9S, 79W)

How do you tell which two points to use? Whether it's North + South OR East +West
and whether you minus or subtract?

(I have no logic, so breaking it down for me would help LOL)

 

[soloooooo]

Is this a serious question?

 

[mrh94]

Is this a serious question?

Yep! hahahahah. Like I said, no logic. Help would be appreciated.

 

[bloophoop]

They'll normally tell you which to use in the question if neither latitude or longtitude matches each other. You use the one that doesn't match eg for (43N, 79W) and (9S, 79W), it would be 43N and 9S, because there is no distance between 79W and 79W. But for your first example, it should say whether to use longtitude or latitude, I'm pretty sure.

Using your second example, the angular distance is 43N + 9S, so if it's N and S you add them to get the angular distance. If it was 43N and 40N, you'd do 43-40. So basically, if they're on opposite sides, it's add, if they're on the same, subtract.
Bad diagram to explain: http://ctrlv.in/129383
To get the angular distance between 43N and 9S, you have to get from 43N down to the equator (0), so that's 43 degrees. Then you also have to go to 9S, which is another 9. So 43+9 is the angular distance.
For 43N and 40N, they're in the same section, so you only have to go down 3 degrees. Don't know if the diagram was necessary but yeah haha.
Same goes for W and E. eg 120W and 40E, it's 120+40 for angular distance. For 120W and 30W, it's 120-30.

So back to eg2, 43N + 9S is 51 degrees. Sub it into the formula of 51/360 x 2 x (pi) x 6400, and you should get an answer in km. Hope that helps!

 

[mrh94]

they'll normally tell you which to use in the question if neither latitude or longtitude matches each other. You use the one that doesn't match eg for (43n, 79w) and (9s, 79w), it would be 43n and 9s, because there is no distance between 79w and 79w. But for your first example, it should say whether to use longtitude or latitude, i'm pretty sure.

Using your second example, the angular distance is 43n + 9s, so if it's n and s you add them to get the angular distance. If it was 43n and 40n, you'd do 43-40. So basically, if they're on opposite sides, it's add, if they're on the same, subtract.
Bad diagram to explain: http://ctrlv.in/129383
to get the angular distance between 43n and 9s, you have to get from 43n down to the equator (0), so that's 43 degrees. Then you also have to go to 9s, which is another 9. So 43+9 is the angular distance.
For 43n and 40n, they're in the same section, so you only have to go down 3 degrees. Don't know if the diagram was necessary but yeah haha.
Same goes for w and e. Eg 120w and 40e, it's 120+40 for angular distance. For 120w and 30w, it's 120-30.

So back to eg2, 43n + 9s is 51 degrees. Sub it into the formula of 51/360 x 2 x (pi) x 6400, and you should get an answer in km. Hope that helps!

thankyou so much :d