A quadrilateral is a shape with four sides, four angles, and four vertices. Quadrilaterals are common in everyday life, appearing in floors, walls, windows, and books. Parallelograms are quadrilaterals where opposite sides are parallel and equal in length; specific types include rectangles, squares, and rhombi. Properties of parallelograms include having diagonals that bisect each other and divide the shape into two congruent triangles.

2. What is Quadrilateral?
A figure formed by joining four points
in a order is called a Quadrilateral. It
has four sides, four angles and four
vertices .

3. Do we see quadrilateral in our
day to day life?
Yes, we see quadrilaterals in our day to day life
. Examples :- the floor, walls, ceiling,
window, paper of our book etc.

4. Parallelograms
Parallelogram is a figure having four sides, four
angles and four vertices. It has opposite
equal and parallel .

5. Different types of quadrilaterals
 When one pair of opposite side of a
quadrilateral are parallel then it is a
trapezium
 When both pairs of opposite sides of a
quadrilateral are parallel then it is a
parallelogram.
 When opposite sides of a parallelogram
are equal then it called a rhombus.

6. Properties of parallelograms
 A diagonal of a parallelogram divides it
into two congruent triangles.
 In a parallelogram opposite sides are
equal.
 In a parallelogram opposite angles are
equal.
 The diagonals of a parallelogram bisect
each other.

7. Mid point theorem
Mid point theorem is used basically in
triangles. It is basically to prove the 2nd
side of the triangle to the 3rd side.

8. Summary
I. Sum of the angles of a quadrilateral is 360.
II. In a parallelogram opposite side, opposite
angle are equal and diagonals bisect each
other.
III. Diagonals of a rectangle bisect each other
and are equal and vice versa.
IV. The line segment joining the mid point of any
two side of a triangle is parallel to the third
side is half of it.

9. Lets do some questions
Q1. The angles of quadrilateral are in the ratio
3:5:9:13. Find all the angles of quadrilateral.
Q2. Show that the diagonals of a square are
equal and bisect each other at right angles.
Q3. The line segment joining the mid point of
two sides of a triangle is parallel to the third
side. (Proof The Above)