In Tacheometer, when the line of sight is inclined and the staff is held vertically, the horizontal distance is given by ________, where f - focal length of object glass; d - distance between optical centre and vertical axis of instrument; S - staff intercept; I - length of image; θ - angle of elevation.
1
\(\frac{f}{i}S{\tan ^2}\theta + (f + d)\tan \theta \)
2
\(\frac{f}{i}S{\cot ^2}\theta + (f + d)\cot \theta \)
3
\(\frac{f}{i}S{\cos ^2}\theta + (f + d)\cos \theta \)
4
\(\frac{f}{i}S{\sin ^2}\theta + (f + d)\sin \theta\)