When a pair of parallel lines is cut with another line known as an intersecting transversal, it creates pairs of angles with special properties. Corresponding angles The lines make an F shape .

Solid Geometry and Conic Sections, with Appendices on Transversals and Harmonic Division; for the Use of Schools. By J. M. Wilson (Macmillan and Co. 1872.) Geometrical Note-Book, ...

When a pair of parallel lines is cut with another line known as an intersecting transversal, it creates pairs of angles with special properties. Corresponding angles The lines make an F shape .