CBSE Class 9 Mathematics/Quadrilaterals.

CBSE Class 9 Mathematics/Quadrilaterals is about the important points about Quadrilaterals. From this you will get an idea about the properties of different type of quadrilaterals.

CBSE Class 9 Mathematics/ Quadrilaterals – Chapter 8
Important points about Quadrilaterals.
Important points to remember:

• A four sided polygon is called a Quadrilateral.
  *A quadrilateral has 4 sides, 4 angles and 4 vertices.
• Sum of the angles of a quadrilateral is 360 degree.
• In a parallelogram,
  i) Opposite sides are equal.
  ii) Opposite angles are equal.
  iii) Diagonals bisect each other.
  iv) A diagonal of a parallelogram divides it into two congruent triangles.
  *Diagonals of a rectangle bisect each other and are equal and vice-versa.
  *Diagonals of a rhombus bisect each other at right angles and vice-versa.
  *Diagonals of a square bisect each other at right angles and are equal, and vice-versa.
  *In a square,
  i) All sides are equal
  ii) All angles are 90 degree.
  iii) Diagonals are equal
  iv) Diagonals bisect each other at right angles.
  *In a Rectangle,
  i) Each angle is 90 degree
  ii) Diagonals are equal
  *In a rhombus,
  i) All sides are equal
  ii) Diagonals bisect each other at right angle
  *In a trapezium,
  i) Only one pair of opposite sides is parallel.
  ii) Trapezium is not a parallelogram
  *In a kite,
  i) Two pairs of adjacent sides are equal
  ii) Kite is not a parallelogram
  *The quadrilateral formed by joining the mid-points of the sides of a quadrilateral, in order, is a parallelogram.
  *Square, rectangle and rhombus are all parallelograms.
  *A square is a rectangle and also a rhombus.
  *A parallelogram is a trapezium.
  *The line segment joining the mid-points of two sides of a triangle is parallel to the third side.