This unit deals with some of the basic concepts of homothety (or enlargement) and some formulae connected to Thales' theorem. Rather than rigorous, step-by-step demonstrations, this unit offers the advantage of proving theories and properties in a straightforward manner.

To conclude the unit, different examples of similarity in triangles and polygons in general is also focused on, through an interactive approach.

There is an introduction to metric relations in a right-angled triangle: the theorem of the sides adjacent to the right angle and the perpendicular height theorem.

• Understand and know how to apply direct and inverse homothety to simple shapes.
  
• Apply Thales' theorem to cases where segments are in proportion to each other.

• Construct similar polygons and work out their related measurements.

• Understand and know how to apply the theorem of the sides adjacent to the right angle and the perpendicular height theorem.