Find the area of the trapezium PQRS with height PQ given in the figure given below
We have, trapezium $P Q R S$, in which draw a line $R T$ perpendicular to $P S$.
where, side, $S T=P S-T P=12-7=5 \mathrm{~m} .$ $[\because T P=P Q=7 \mathrm{~m}]$
$\begin{array}{lll}\text { In right angled } \Delta S T R, & (S R)^{2}=(S T)^{2}+(T R)^{2} & \text { [by using Pythagoras theorem] }\end{array}$
$\Rightarrow \quad(13)^{2}=(5)^{2}+(T R)^{2}$
$\Rightarrow \quad(T R)^{2}=169-25$
$\Rightarrow \quad(T R)^{2}=144$
$\therefore$ $T R=12 \mathrm{~m}$
[taking positive square root because length is always positive]
Now, area of $\Delta S T R=\frac{1}{2} \times T R \times T S$ $\left[\because\right.$ area of triangle $=\frac{1}{2}$ (base $\times$ height) $]$
$=\frac{1}{2} \times 12 \times 5=30 \mathrm{~m}^{2}$
Now, area of rectangle $P Q R T=P Q \times R Q=12 \times 7$
$[\because$ area of a rectangle $=$ length $\times$ breadth $]$
$[\because P Q=T R=12 \mathrm{~m}]$
$=84 \mathrm{~m}^{2}$
$\therefore$ Area of trapezium = Area of $D S T R+$ Area of rectangle $P Q R T$
$=30+84=114 \mathrm{~m}^{2}$
Hence, the area of trapezium is $114 \mathrm{~m}^{2}$.