Question

In the figure, $ABCD$ is a paralle-logram, $AE\perp DC$ and $CF\perp AD$. If $AB=16$ cm, $AE=8$ cm and $CF=10$ cm, find $AD$.

Answer 1

Area of parallelogram $ABCD=AB\times AE$

$=16\times 8$sq.cm

$=128$sq.cm

Also, area of parallelogram $ABCD=AD\times FC$

$=(AD\times 10)$sq.cm

$\therefore AD\times 10=128$

$\Rightarrow AD=\frac{128}{10}=12.8$ cm