Two particles, 1 and 2, move with constant velocities `v_1` and `v_2` along two mutually perpendicular straight lines toward the intersection point O. At the moment `t=0` the particles were located at the distances `l_1` and `l_2` from the point O. How soon will the distance between the particles become the smallest? What is it equal to?

Explanation

To solve the problem step by step, we need to analyze the motion of the two particles and find the time at which the distance between them is minimized, as well as the value of that minimum distance.

### Step 1: Understand the setup
We have two particles moving towards a common point O along two perpendicular lines. Particle 1 starts at a distance \( l_1 \) from O and moves with velocity \( v_1 \). Particle 2 starts at a distance \( l_2 \) from O and moves with velocity \( v_2 \).

### Step 2: Define the positions of the particles
At time \( t \):
- The position of Particle 1 from point O is \( l_1 - v_1 t \).
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