# Mensuration Class 8

Mensuration class 8 – By constructing EC || AB, we can split the given figure (AEDCBA) into two parts(Triangle ECD right angled at C and Rectangle AECB), Here, b = a + c = 30 m

Now, Area of Triangle DCE:

$\frac{1}{2}\times CD\times EC=\frac{1}{2}\times c\times h=\frac{1}{2}\times 10\times 12=60\;m^{2}$

Also, Area of rectangle AECB = $AB\times BC=h\times a=12\times 20=240\;m^{2}$

Therefore, Area of trapezium AEDB = Area of Triangle DCE + Area of rectangle AECB = 60 + 240 = 300 $300\;m^{2}$

Diagonal AC divides the given quadrilateral into two triangles i.e. Triangle ABC and Triangle ADC.

Now, Area of Quadrilateral ABCD = Area of Triangle ABC + Area of Triangle ADC.

= $\frac{1}{2}\times AC\times h_{1}+\frac{1}{2}\times AC\times h_{2}=\frac{1}{2}\times d\times (h_{1}+h_{2})$

Where, d = The length of diagonal of a quadrilateral.

### Mensuration class 8 Examples

#### Practise This Question

Which of the following shows 114 and 258 on a number line?