Identify the geometry

In a right-angled triangle formed by the slope, the horizontal distance is the adjacent side to the angle of inclination.

$\text{Adjacent} = \text{Hypotenuse} \times \cos(\theta)$

Substitute given values

Substitute the sloping distance $L = 100\text{ m}$ and the angle $\theta = 15°$ into the trigonometric formula.

$D = 100 \times \cos(15°)$

Calculate the result

Using the value $\cos(15°) \approx 0.96592$, calculate the final horizontal distance.

$D = 100 \times 0.96592 = 96.592\text{ m}$