Question

Using a compass and straight edge only mark two points A and B. Draw the line `l` through them and find another point C on `l` such that AB = BC?

Answer 1

Draw a line from A extending through B using the straight edge.
Use compass with center B and radius |AB| to draw a circle.
C is the point of intersection of circle and the line (other than point A)

Explanation:

(see image)