State any two ways to measure directions
Answers
Answer:
compass, north and south
Explanation:
Answer:1.MEASURING HORIZONTAL DISTANCES
Measuring distances along straight lines
1. In topographical surveys, you measure distances along straight lines. These lines either join two fixed points or run in one direction starting from one fixed point. They are plotted in the field with pegs, pillars or ranging poles.
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Expressing distances as horizontal measurements
2. You should always measure distances as horizontal distances. You may have to measure on ground which has no slope, or only a very small slope that is less than or equal to 5 percent (see Section 4.0). The distance measured on this type of ground will be equal to or very close to the horizontal distance. When the slope of the terrain is greater than 5 percent, however, you will have to find the horizontal distance. To do this, you must either correct any measurements you made along the ground (see Section 4.0) or use another method of measurement (see following sections). Unlevelled ground also requires particular methods of measurement.
Measuring distances along lines that run through obstacles
3. Usually, you will be able to reach all the points of the straight line you want to measure. But in some cases an obstacle such as a lake, a river or a cultivated field will be in the way, and you will have to take indirect measurements. This means that you will calculate horizontal distances along the original straight line (see Section 2.9).
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Chaining with a rope
Choosing the most suitable method
4. There are many good ways to measure distances. The method of measurement you use will depend on several factors:
the accuracy of the result needed;
the equipment you have available, to use;
the type of terrain you need to measure.
In the following sections, you will learn how to use the various methods of measurement. Table 1 will also help you to compare these methods and to select the one best suited to your needs.
TABLE 1
Distance measurement methods
Section1
Method
Distance
Error2 per 100 m2
Remarks
Equipment3
22*
Pace count
Medium to long
1 to 2 m or more
For quick, rough estimates
None
22*
Pacing with a passometer or podometer
Long
1 to 2 m or more
For quick, rough estimates
Passometer or podometer
21*
Ruler
Short
0.05 to 0.10 m
Especially useful for sloping ground
Ruler (mason's level, plumb line)
23**
Chaining using a rope
Medium to long
0.5 to 1 m
Cheap
Liana or rope, string, marking line
24**
Chaining using a band or tape
Medium to long
less than 0.05 m
Best results with steel lines
Steel band, measuring tape
25**
Chaining using a chain
Medium to long
0.02 to 0.10 m
Stronger quality
Surveying chain
27***
Clisimeter
Medium
1 to 2 m
For quick and rough estimates
Clisimeter (lyra-)
(2 m stadia staff)
28***
Stadia
Medium to long
0.1 to 0.4 m
For quick and accurate measures
Telescope with stadia hairs, levelling staff
1 * Simple ** More difficult *** Most difficult.
2 Error increases as the terrain becomes more difficult (slope, vegetation, obstacles).
3 In addition to ranging poles (setting out the line), marking pegs (intermediate points), and notebook/pencil. In italics, equipment you can build yourself, as explained in text.
Calculating perimeter lengths
5. The perimeter of an area is its outer boundary. The length of the perimeter of regular geometrical figures can be calculated from the mathematical formulas given in Annex 1, at the end of this manual.
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AB + BC + CD + DE + EF + FA = Perimeter ABCDEFA
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Perimeter WXYZW