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.

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