Understanding Quadrilaterals - Revision Notes

CBSE Class 8 Mathematics
Revision Notes
Chapter – 3
Understanding Quadrilaterals

  • Parallelogram: A quadrilateral with each pair of opposite sides parallel.
    (1) Opposite sides are equal.
    (2) Opposite angles are equal.
    (3) Diagonals bisect one another.
  • Rhombus: A parallelogram with sides of equal length.
    (1) All the properties of a parallelogram.
    (2) Diagonals are perpendicular to each other.
  • Rectangle: A parallelogram with a right angle.
    (1) All the properties of a parallelogram.
    (2) Each of the angles is a right angle.
    (3) Diagonals are equal.
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  • Square: A rectangle with sides of equal length.
    (1)  All the properties of a parallelogram, rhombus and a rectangle. 
  • Kite: A quadrilateral with exactly two pairs of equal consecutive sides
    (1) The diagonals are perpendicular to one another
    (2) One of the diagonals bisects the other.
    (3) In the figure  but .
  • Trapezium: A quadrilateral having exactly one pair of parallel sides.
  • Diagonal: A simple closed curve made up of only line segments. A line segment connecting two non-consecutive vertices of a polygon is called diagonal.
  • Convex : The measure of each angle is less than .
  • Concave: The measure of at least one angle is more than 
  • Quadrilateral: Polygon having four sides.
  • Element of quadrilateral:
    (i) Sides: Line segments joining the points.
    (ii) Vertices: Point of intersection of two consecutive sides.
    (iii) Opposite sides: Two sides of a quadrilateral having no common end point.
    (iv) Opposite Angles: Two angles of a quadrilateral not having a common arm.
    (v) Diagonals: Line segment obtained by joining the opposite vertices.
    (vi) Adjacent Angles: Two angles of a quadrilateral having a common arm.
    (vii) Adjacent Sides: Two sides of a quadrilateral having a common end point.