When examining transformations of the plane in geometry, teachers typically have students experiment with transformations of polygons. Students are usually quick to notice patterns with ordered pairs. The Common Core State Standard, Geometry, Congruence 2 (G-CO.2), requires students to describe transformations as functions that take points in the…

The third in a series of four articles, this is concerned with establishing the main properties of the general linear transformation of the plane, equations of lines, area, and change of axes. For earlier articles, see MT number 57, Winter 1971, pp. 14-19 and MT number 58, Spring 1972, pp. 49-55. (DT)

The first of three articles showing how inductively-obtained results in transformation geometry may be organized into a deductive system. This article discusses two approaches to enlargement (dilatation), one using coordinates and the other using synthetic methods. (MM)

The basic ideas of the theory of manifolds is illustrated using elementary geometry. (MM)