Included angle from whole-circle bearings: If the whole-circle bearings of lines OA and OB are 16° 10' and 332° 18' respectively, what is the included angle BOA (taken at O from OB to OA, choosing the smaller angle)?

Difficulty: Easy

Correct Answer: 43° 52'

Explanation:


Introduction / Context:
Computing included angles from whole-circle bearings (WCB) is a routine step in traverse adjustment. Careful attention to the direction of subtraction and selection of the smaller angle avoids common sign and wrap-around mistakes.


Given Data / Assumptions:

  • Bearing(OA) = 16° 10' (WCB).
  • Bearing(OB) = 332° 18' (WCB).
  • Included angle BOA is the turn from OB to OA at the station O.


Concept / Approach:
To turn from OB to OA, advance from 332° 18' up to 360°, then continue to 16° 10'. The net turn is (360° − 332° 18') + 16° 10' = 27° 42' + 16° 10' = 43° 52'. Always normalize within 0°–360° and choose the interior (smaller) angle unless otherwise specified.


Step-by-Step Solution:

Compute wrap-around: 360° − 332° 18' = 27° 42'.Add OA: 27° 42' + 16° 10' = 43° 52'.Therefore, the included angle BOA = 43° 52' (smaller interior angle).Select the matching option.


Verification / Alternative check:
Direct difference |16° 10' − 332° 18'| = 316° 08' (exterior angle); 360° − 316° 08' = 43° 52', confirming the result.


Why Other Options Are Wrong:

  • 316° 10' and 348° 08': incorrect arithmetic or wrong direction of subtraction.
  • 158° 28': not consistent with either the interior or exterior difference for these bearings.


Common Pitfalls:
Forgetting wrap-around across 0°; mixing quadrantal and whole-circle systems; choosing the exterior angle by mistake.


Final Answer:
43° 52'

More Questions from Surveying

Discussion & Comments

No comments yet. Be the first to comment!
Join Discussion