A topographic quadrangle is a 30' series map (it covers 30' longitude and latitude). If the western longitude boundary is 120 degrees 02 feet 30 inches, what is the longitude of the eastern boundary?
That depends upon which hemisphere the map depicts -- Eastern or Western?
It doesn't specify. Can you tell me the answer to both?
Don't you mean, 120 degrees, 2 minutes, 30 seconds?
http://en.wikipedia.org/wiki/Latitude
In the Western Hemisphere, the longitude numbers get larger as you go west. So 120 degrees, 02 minutes, 30 seconds minus 30 degrees equals 90 degrees, 02' 30".
In the Eastern Hemisphere add 30 degrees to the boundary longitude.
Thank you.
To determine the longitude of the eastern boundary of the topographic quadrangle, we need to know the longitude difference covered by the map. Given that the quadrangle is a 30' series map, we can infer that it covers a 30-minute (0.5-degree) difference in longitude.
To find the longitude of the eastern boundary, we need to add this longitude difference to the western longitude boundary.
The western longitude boundary is given as 120 degrees 02 feet 30 inches.
Let's convert the feet and inches values to minutes, as it is a more common unit for measuring longitude:
1 foot = 12 inches
1 minute = 1/60 degree
So, 02 feet = 02 x 12 = 24 inches, and 30 inches is equivalent to 30/12 = 2.5 feet.
Next, we can convert the additional feet and inches to minutes:
24 inches = 24/12 = 2 feet = 2 minutes
2.5 feet = 2.5 minutes
Now we can calculate the longitude of the eastern boundary:
Eastern Longitude = Western Longitude + Longitude Difference
Eastern Longitude = 120 degrees 02 feet 30 inches + 0.5 degrees + 2 minutes + 2.5 minutes
Add the minutes together: 2 minutes + 2.5 minutes = 4.5 minutes
So, the longitude of the eastern boundary is 120 degrees 04 feet 30 inches.
Please note that since longitude measures east and west, the minutes and seconds values should refer to the number of minutes and seconds east of the whole degrees, whereas the feet value adds to the degrees.