Transferring a length from one point to another
Back to constructions homepage
Back to Geometry homepage
Now you can use the Equilateral Triangle Construction to transfer a length from one point to another. Given a line segment XY and a point Z, can you construct a point W such that |XY|=|WZ|? Equivalently, can you draw a circle centred at Z with radius |XY|?
As an example, the diagram below contains a line segment AB and a circle centred at C with radius AB. Any point D on this circle will automatically satisfy |AB|=|CD|.
Just as for the previous exercise, the tools you can use are limited, since all you have is a ruler and compass as well as your knowledge of how to construct an equilateral triangle.
Hint. This exercise is explained in Euclid Book I, Proposition 2.