Question

In the trapezium ABCD, AB||DC and AB=2 CD. IF the area of $△AOB=84{cm}^2$, find the area of $△COD$.

Answer 1

as $△AOB,△COD$ form a trapezium

$\therefore \frac{arAOB}{arCOD}={\left(\frac{AB}{DC}\right)}^2={\left(\frac{2CD}{DC}\right)}^2$

$\frac{84}{arCOD}={\left(\frac{AB}{DC}\right)}^2=\left(\frac{4}{1}\right)$

$\therefore ar△COD=\frac{84}{4}=21sq.units$