Welcome to JSS2 Second Term!

We are building on our work from First term as we learn more about Basic Technology.

In today’s class, We will be discussing QUADRILATERALS. We hope you enjoy the class!

Quadrilateral Definition

A quadrilateral is a plane figure that has four sides or edges, so having four corners or vertices. Quadrilaterals will typically be of standard shapes with four sides like rectangle, square, trapezoid, and kite or irregular and uncharacterized as shown below:


Types of Quadrilaterals

There are many types of quadrilaterals. As the word ‘Quad’ means four, all these types of a quadrilateral have four sides and the sum of angles of these shapes is 360 degrees.

    1. Trapezium
    2. Parallelogram
    3. Squares
    4. Rectangle
    5. Rhombus
    6. Kite


Another way to classify the types of quadrilaterals are:

  1. Convex Quadrilaterals: Both the diagonals of a quadrilateral are completely contained within a figure.
  2. Concave Quadrilaterals: At least one of the diagonals lies partly are entirely outside of the figure.
  3. Intersecting Quadrilaterals: Intersecting quadrilaterals are not simple quadrilaterals in which the pair of non-adjacent sides intersect. This kind of quadrilaterals are known as self-intersecting or crossed quadrilaterals

QUADRILATERALS basic tech classnotesng


Quadrilateral Properties

A quadrilateral is a 4-sided plane figure. Below are some important properties of quadrilaterals:

  • Every quadrilateral has 4 vertices, 4 angles, and 4 sides
  • The total of its interior angles = 360 degrees
  • A quadrilateral with four equal sides and four right angles is a square
  • A quadrilateral that has opposite sides equal and measure of every angle is 90 degrees is a rectangle
  • Parallelogram, trapezium, rhombus, and kite are other examples of quadrilaterals


Let us understand in a better way with the help of an example:

  • Four sides: AB, BC, CD, and DA
  • Four vertices: Points A, B, C, and D
  • Four angles: ∠ABC, ∠BCD, ∠CDA, and ∠DAB
  • ∠A and ∠B are adjacent angles
  • ∠A and ∠C are the opposite angles
  • AB and CD are the opposite sides
  • AB and BC are the adjacent sides

Quadrilateral Formula

What is the area of the quadrilateral?

Area of the quadrilateral is the total space occupied by the figure. There are different types of quadrilaterals. Let us study area formula each of them:

Area of a Parallelogram Base x Height
Area of a Rectangle Length x Width
Area of a Square Side x Side
Area of a Rhombus 1/2 x Diagonal 1 x Diagonal 2 OR Length x Height
Area of a Kite 1/2 x Diagonal 1 x Diagonal 2

QUADRILATERALS formula basic tech classnotesng


We have come to the end of this class. We do hope you enjoyed the class?

Should you have any further question, feel free to ask in the comment section below and trust us to respond as soon as possible.

In our next class, we will be talking about Plane figures Polygons. We are eager to meet you there.


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