Unit four is about right triangles and the relationships that exist between its sides and angles. Students apply their understanding of similarity, from unit three, to prove the Pythagorean Theorem. Trigonometric functions, which are properties of angles and depend on angle measure, are also explained using similarity relationships. Students determine when to use trigonometric ratios, Pythagorean Theorem, and/or properties of right triangles to model problems and solve them. Throughout the unit, students should be applying similarity and using inductive and deductive reasoning as they justify and prove these right triangle relationships.

Essential Questions:

- What relationships exist between the sides of similar right triangles?
- What is the relationship between angles and sides of a right triangle?