Triangles
Class 9 · Mathematics · 5 lessons
This chapter, Triangles, is part of the Class 9 Mathematics syllabus under CBSE, Telangana and Andhra Pradesh boards. It contains 5 lessons — starting with Introduction to Congruence of Triangles, Exercise 7.1 — Congruency Problems, Exercise 7.2 — Properties of Triangles, and more — each with free, step-by-step PDF notes you can study directly in the browser or present in class in fullscreen mode. Work through the lessons in order below; later exercises in this chapter generally build on the concepts introduced in the earlier ones.
Introduction to Congruence of Triangles
Congruence of triangles and criteria for congruence.
Exercise 7.1 — Congruency Problems
Problems based on congruency of triangles.
Exercise 7.2 — Properties of Triangles
Some more properties of triangles.
Exercise 7.3 — More Congruence Criteria
More criteria for congruence of triangles.
Exercise 7.4 — Triangle Inequalities
Inequalities in a triangle.