Given two unequal straight lines, to cut off from the greater a straight line equal to the less.
• Start with the line segments AB and C, with AB greater than C.
• Let line AD be created from point A, equal to line C (see Proposition 2).
• Create the circle DEF around point A with a radius of AD.
• Place point E on the intersection of the circle DEF and the line AB.
The line AE has been created on line AB equal to line C.