## 4. Construction

Given two fixed points $A$ and $B$. How to draw two parallel lines through these points, such that they are at a given distance $l$ from each other (of course, less than the distance from $A$ to $B$)?
4. Construct a circle with diameter $A B$ and an arc with center $A$ and radius $l$. Let $C$ be the point of intersection of this arc with the circle. Draw the line $B C$, and through $A$ draw a line parallel to $B C$. The length $A C$ (i.e., $l$)

![](https://cdn.mathpix.com/cropped/2024_05_21_fe999c0fe2ad81fc5164g-150.jpg?height=677&width=948&top_left_y=1686&top_left_x=568)

is equal to the distance between the obtained parallel lines, which is what was required by the problem.