We often come across two triangles that share the same
proportions, i.e. the angles are alike though their sizes differ.
These are called similar triangles. The simplest method of
illustrating two similar triangles is first to draw a triangle, and
then to draw a straight line so that we now has a smaller triangle
within the large one.
Triangles that are similar are shown as
The sides that have the same relative position in the similar
figures, like A and D in the triangle above are called
corresponding sides. The ratios of the corresponding sides of
similar figures are equal which means that they are
proportions.
Figures that have both the same size and shape are called
congruent figures and are indicated as
