30
Sep
Example 7: In ∆ ABC, D, E and F are respectively the mid-points of sides AB, BC and CA (see Fig. 8.27). Show that ∆ ABC is divided into four congruent triangles by joining D, E and F.
Chapter 8 – Quadrilaterals
This playlist covers all the questions, concepts, theorems and examples of chapter 8 (Quadrilaterals) of class 9, NCERT textbook. Click a thumbnail to watch the tutorial.
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Theorem 8.1, chapter 8 Class 9, Diagonal of a parallelogram divides it into two congruent triangles
Section 8.2, Class 9 – Angle sum property of quadrilateral | Sum of angles is 360 degrees
Theorem 8.2 chapter 8 class 9 | Prove that opposite sides of a parallelogram are of equal length
Theorem 8.3, ch 8 Class 9, Pair of opposite sides of quadrilateral is equal, it's a parallelogram
Equal Or Congruent ? Lines and Angles
Theorem 8.4, chapter 8 Class 9, How to prove that opposite angles of a parallelogram are congruent
Theorem 8.5, ch 8 Class 9, Pair of opposite angles of quadrilateral is equal, it's a parallelogram
Theorem 8.6, ch 8 Class 9, How to prove that the diagonals of a parallelogram bisect each other
Theorem 8.7, ch 8 Class 9, Diagonals of quadrilateral bisect each other, then it's a parallelogram
Class 9 | Chapter 8 | Example 1 Explanation | NCERT| Quadrilaterals – Each angle of rectangle is 90°
Example 2, Chapter 8, Class 9 – Diagonals of a square / rhombus are perpendicular to each other
Class 9 | Chapter 8 | Example 3 Explanation | NCERT| Quadrilaterals
Class 9 | Chapter 8 | Example 4 Explanation | NCERT| Quadrilaterals
Class 9 | Chapter 8 | Example 5 Explanation | NCERT Maths | Quadrilaterals
Theorem 8.8, Class 9, A pair of opp sides of quadrilateral is equal+parallel ⇒ it's a parallelogram
Question 1, Exercise 8.1, Ch 8, Class 9 | Parallelogram's diagonal are equal, then it's a rectangle
Question 2, Exercise 8.1, Ch 8, Class 9 | Diagonals of square are equal, bisect at right angles
Question 3, Exercise 8.1, Ch 8, Class 9 | Diagonal of parallelogram bisect the angles | Rhombus
Question 4, Ex 8.1, Ch 8, Class 9, Diagonal of rectangle bisects opposite angles, it is square
Question 5, Exercise 8.1, Ch 8, Class 9 Maths | Questions on Parallelograms and Congruent Triangles
Question 6, Exercise 8.1, Ch 8, Class 9 Maths | Questions on Parallelograms and Congruent Triangles
Question 7, Exercise 8.1, Ch 8, Class 9 Maths | Ques on Trapezium, Parallelogram, Congruent Triangle
Theorem 8.9 Chapter 8 Class 9 | MID POINT THEOREM | Proof in 2 different ways
Theorem 8.10 Chapter 8 Class 9 | CONVERSE OF MID POINT THEOREM | Proved by 3 different methods
Class 9 | Chapter 8 | Example 6 Explanation | NCERT Maths | Quadrilaterals
Class 9 | Chapter 8 | Example 7 Explanation | NCERT Maths | Quadrilaterals
Question 1 Exercise 8.2 Chapter 8 Class 9 | Proof | NCERT | Quadrilaterals
Question 2 Exercise 8.2 Chapter 8 Class 9 | Proof | NCERT | Quadrilaterals
Question 3 Exercise 8.2 Chapter 8 Class 9 | Proof | NCERT | Quadrilaterals
Question 4 Exercise 8.2 Chapter 8 Class 9 | Proof | NCERT | Quadrilaterals
Question 5 Exercise 8.2 Chapter 8 Class 9 | Proof | NCERT | Quadrilaterals
Question 6 Exercise 8.2 Chapter 8 Class 9 | Proof | NCERT | Quadrilaterals
