Site pages
Current course
Participants
General
18 February - 24 February
25 February - 3 March
4 March - 10 March
11 March - 17 March
18 March - 24 March
25 March - 31 March
1 April - 7 April
8 April - 14 April
15 April - 21 April
22 April - 28 April
Obstacle to chaining but not ranging 2
Obstacle to chaining and ranging
Obstacle to chaining but not ranging
When it is not possible to chain round the obstacle
I Method
Select point B on one side and A and C on the other side(Fig(a)). Erect AD and CE as perpendiculars to AB and range B, D and E in one line. Measure AC, AD and CE. If a line DF is drawn parallel to AB, cutting CE in F perpendicularly, then triangles ABD and FDE will be similar.
II Method
Erect a perpendicular AC and bisect it at D (Fig(b)). Erect perpendicular CE at C and range E in line with BD. Measure CE. Then AB = CE
Last modified: Friday, 29 April 2011, 8:44 AM