Lesson: Parallel Lines and Transversals: Proportional Parts Mathematics • First Year of Secondary School

Students will be able to

• understand how to apply the basic proportionality theorem (Thales’s theorem) to find a missing length of a line segment in a transverse line cut by parallel lines
  • including problems involving algebraic variables as side lengths,
  • including problems that use the properties of polygons,
• understand that if the lengths of the segments of one transversal are equal, then the lengths of the segments of any other transversal are also equal (Thales’s special theorem).