Survey Question

[odu_engineer]

Two coordinates give:

A: 1035N, 1585W

B: 435N, 900W

Find bearing of AB:

inverse tan (delta Y / delta X) gives 48 degrees 47 minutes 4 seconds

My question: how do I get the direction associated with this bearing?

Thank you in advance for your response!

 

[civilized_naah]

From A to B, change in northing is negative (i.e.) heading south. Change in easting is positive (1585W can be considered -1585E & 900W can be considered -900E, therefore change in easting is +685, i.e. headed east.)

Therefore the line AB heads southeast.

Since you calculated theta as inverse tan (del Y/del X), therefore the angle 48d47m04s is the angle with the X axis (EAST). Bearings are stated with respect to north or south meridian

Angle between AB and the south meridian is 90d - 48d47m04s = 41d12m56s

Therefore bearing is S 41d12m56s E

 

[Jayman_PE]

I would say the best approach to these problems is to recognize the direction asked (A to B, or B to A), then note the coordinate directions (i.e. Northing, Easting or Northing, Westing, etc.) and do a rough sketch, doesn't have to be exact. Once you recognize direction it's just an elementary trig problem. The key is know the direction!