Quadrilateral

1. Development of e-content based on
QUADRILATERAL
Objectives
To find the area of a quadrilateral.
Subject Concept Mapping
Area =1
/2 d1d2 Area= a2
Area=l ×b Area = b×b Area=1
/2 h(a+b)
Summary
To find the area of a quadrilateral, divide the quadrilateral by
drawing a diagonal and we get two triangles. If we add the areas of these two triangles we get the area
of that quadrilateral. Here the diagonal’s length is taken as “d” and the height from the opposite
vertices are “p1“and “p2 “respectively.
Therefore the area of quadrilateral = Sum of the area of two triangles.
= (1
/2 × d × p1) + (1
/2 × d × p2)
= 1
/2 d (p1+p2)
Quadrilateral
Rhombus Square Rectangle Parallelogram Trapezium

2. Text
Text book of standard VIII , SCERT.
Case study
 Gary kotze – Investigating Shape And Space In Mathematics : a case study.
 South African Journal Of Education – VOL 27(1) 19-35.
FAQS
1. Define quadrilateral?
2. The figure obtained by joining the mid-points of the sides of a rhombus, taken in order is?
3. What is the formula for the area of a quadrilateral?
4. Write any 3 different types of quadrilaterals?
5. Total sum of the angle of a quadrilateral is________.
ANSWERS
1. A closed four sided shape is called a quadrilateral.
2. Square.
3. Area = 1
/2 d( P1+P2).
4. Square, Parallelogram, Rhombus
5. 3600
.
Video Or Audio
https://www.youtube.com/watch?v=rXZcYHVwkqI
Assignment
1. The quadrilateral PQRS, PR = 10 cm, the heights from the two vertices Q,S to PR are 14cm &
16cm.Find the area of the quadrilateral?
2. The quadrilateral ABCD, the heights from the two vertices B & D to AC are 10 cm & 14
cm.Area the quadrilateral is 144 cm2
.find AC?
References
 A.K Jobbing’s, ”Quadric Quadrilaterals”; The mathematical gazette VOL
81,NO491(july,1997),pp.220-224.
 www.siveco.ro.

3. Glossary links
 Vertices: The points where the size of a quadrilateral meets are called vertices.
 Edges: The sides of the quadrilateral are called edges.
 Diagonal: the line segment drawn from one vertex of a quadrilateral to the opposite vertex is
called diagonal of the quadrilateral.
 Quadrilateral: It is a closed plane figure bounded by four line segments.
Downloads
https://www.youtube.com/watch?v=rXZcYHVwkqI
Blog
Kellysvideosforgcom.blogspot.in