A 4-sided polygon is a quadrilateral


Polygon is a simple closed figure made of line segments


A quadrilateral has

  • 4 vertices − A, B, C, D
  • 4 sides − AB, BC, CD, DA
  • 4 angles − ∠A, ∠B, ∠C, ∠D

Opposite sides

  • AB & CD are opposite sides
  • AD & BC are opposite sides

Adjacent sides

  • AB, BC are adjacent sides
  • AB, AD are adjacent sides
  • BC, CD are adjacent sides
  • CD, DA are adjacent sides"
    Quadrilaterals - Part 2

Opposite angles

  • ∠A, ∠C are opposite angles
  • ∠B, ∠D are opposite angles


Quadrilaterals - Part 3


Adjacent angles

  • ∠A, ∠B are adjacent angles.
  • ∠A, ∠D are adjacent angles.
  • ∠B, ∠C are adjacent angles.
  • ∠C, ∠D are adjacent angles.


Diagonals of a quadrilateral

Quadrilaterals - Part 4

Line joining two opposite vertices of a quadrilateral is a diagonal.


Here, AC, BD are diagonals of the quadrilateral.

And they meet at point O.

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.