Section 4: Soil and Water Conservation Engineering
Surveying and Levelling
Subtopic: Measurement of angles and bearings
Question Statement:
If the Whole Circle Bearing (WCB) of survey line AB is $245^\circ 30'$, its Reduced Bearing (Quadrantal Bearing, RB) is:
Options:
(A) $\text{S } 65^\circ 30' \text{ W}$
(B) $\text{W } 65^\circ 30' \text{ S}$
(C) $\text{S } 25^\circ 30' \text{ W}$
(D) $\text{N } 65^\circ 30' \text{ W}$
Answer Key:
A
Step-by-Step Solution & Explanation
1. WCB lies between $180^\circ$ and $270^\circ$, placing the survey line in the South-West (SW) third quadrant.
2. In the third quadrant:
$RB = \text{S } (WCB - 180^\circ) \text{ W}$
$RB = \text{S } (245^\circ 30' - 180^\circ 00') \text{ W} = \text{S } 65^\circ 30' \text{ W}$
Option A is correct.