11
．
Measure the distance on the ground
In accordance to the principle mentioned under point 9 10 ,it is possible to define the distance on the ground
between two well-visible points on the ground.
For example ,you can measure the width of a farm house ,the length of a bridge,etc.There is one necessary
condition to measure the distance from your own position to that of the object:the line running from these two
positions must be as perpendicular as possible to the side
of the object to be measured.
Example:
At a distance of 4000m, a bridge spans a river,transverse to
the line of vision.How long is the bridge if an angle of 6°is
measured from the right to the left river bank?
6°=10% or 1 /10
4000x10%=400m OR 4000X1 /10=400m
To Next Page
Loading...