Answer
As the angle $\alpha$ of the headlight alignment increases, the value of $L$ decreases.
Work Step by Step
$L = \frac{(\theta_2-\theta_1)~S^2}{200~(h+S~tan~\alpha)}$
The angle $\alpha$ is the angle of the headlight alignment above the horizontal. As the angle $\alpha$ increases, the value of $tan ~\alpha$ increases. As the denominator increases, the value of $L$ decreases.
As the angle $\alpha$ of the headlight alignment increases, the value of $L$ decreases.
