is a transformation which changes the size of an object without
changing its shape, rather as a projector enlarges the details of
a photographic slide onto a screen.
An enlargement of a diagram can be constructed by first drawing
lines from a point O, the center of enlargement, through points
of the figure such as A, B and C, then marking off the image
points A1 B1 C1 so that OA1
= kOA, OB1 = kOB where k is the scale factor of
the enlargement. In the example shown, triangle ABC has been
enlarged with scale factor k = 2. (k is sometimes known as
the linear scale factor).
The center of the
enlargement may be a point outside the object, inside it, or on
its boundary. Also the scale factor can be negative. In this case
it is still true that for every point P its image point P1
is given by OP1 = kOP.