Using Euclidean Compass
Construct the circle centered at C whose radius equals the length of AB using straightedge and Euclidean compass only.
Note: According to Euclid's Elements, the construction can be done by first drawing the equilateral triangle as shown in the applet.
Remark: This construction implies that straightedge and Euclidean compass can "carry the length" to another point just like a modern compass. Therefore, anything that can be constructed by straightedge and modern compass can certainly be constructed by straightedge and Euclidean compass. In other words, constructions using straightedge and modern compass can also be called Euclidean constructions.