This document discusses how to find the shortest distance between two points on Earth's surface. It explains that the shortest path is along a great circle, using the example of finding the distance between two points that are 180 degrees of longitude apart and at the same latitude of 37 degrees north. The distance is calculated as 180 degrees multiplied by 60 nautical miles per degree, equaling 10,800 nautical miles. It then calculates the distance between the same two points as the angle of their great circle arc, which is 106 degrees, multiplied by 60 nautical miles per degree, equaling 6,360 nautical miles.

1. EARTH AS A SPHERE
9.4 Understand and use the
concept of distance on the
surface of the earth to solve
problems

2. LEARning OuTcOmES
Find the shortest distance
between two points on the
surface of the earth.

3. A B
(37o
N, 54o
W)
(37o
N, 126o
E)

4. A B

5. A B
(37o
N, 54o
W)
(37o
N, 126o
E)
180o
Answer

6. The distance between A and B
= 180o
x 60’
= 10 800 nautical mile

7. A B

8. A B
37o
37o
O
∠AOB
Next
0o

9. ∠AOB = 180 – (37o
x 2)
= 106o
Back

10. The distance between A and B
= 106o
x 60’
= 6 360 nautical mile

11. ConClusion
The shortest distance from
one point to another on the
surface of the earth is along a
great circle.