To place at a given point (as an extremity) a straight line equal to a given straight line.
• Start with the point A and line segment BC.
• Connect point A to point B.
• Construct the equilateral triangle DAB on line AB (see Proposition 1).
• Extend line DA to create line AE, and extend line DB to create line BF.
• Create the circle CGH around point B with a radius of BC.
• Create the circle GKL around point D with a radius of DG.
The line AL has been created equal to the given straight line BC from point A.