The multiplying constant of tachometric instrument is 100 and the staff is held vertically. If the staff reading at point ‘A’ are 1.36, 1.915, 2.47 respectively and the measured vertical angle is 10° 30’, what is the distance between instrument station and point A? (Use Cos10° 30’ = 0.983 and Sin10° 30’ = 0.182)
1
168 m
2
150 m
3
107 m
4
90 m