Calculate Staff Intercept ($s$) and Central Reading ($r$)

The staff intercept $s$ is the difference between the top and bottom staff readings. The central staff reading $r$ is the middle reading.

$s = 3 - 1 = 2\text{ m}, \quad r = 2\text{ m}$

Calculate Vertical Distance ($V$)

For an inclined sight with a vertical staff using an analectic lens ($k = 100, c = 0$), the formula for vertical component $V$ is $V = \frac{k \cdot s}{2} \sin(2\theta)$.

$V = \frac{100 \times 2}{2} \sin(2 \times 5°) = 100 \sin(10°) \approx 17.364\text{ m}$

Calculate R.L of the Staff Station

Applying the tacheometric leveling formula for an angle of elevation: $\text{R.L of Station} = \text{R.L of BM} + h + V - r$.

$\text{R.L} = 100 + 1.5 + 17.364 - 2 = 116.864\text{ m}$