6. Triangles

Triangles are one of the most important shapes in geometry, and this chapter mainly focuses on the similarity of triangles. Two triangles are said to be similar if their corresponding angles are equal and their sides are proportional. Students learn important criteria for similarity such as AA (Angle–Angle), SAS (Side–Angle–Side), and SSS (Side–Side–Side).

 

The chapter also explains important results like the Basic Proportionality Theorem (Thales’ theorem) and the Pythagoras theorem, which relates the sides of a right-angled triangle. These concepts help in solving many geometric problems and are useful in practical fields such as architecture, engineering, surveying, and construction.