Question

The parallel sides of a trapezium are20 cm and 10 cm . Its nonparallel sides are both equal each bieng 13 cm . Find the area of tapezium

Answer 1

first construct a parallel line in trapezium to one of its non parallel side
using heron's formula
s=18 cm
$\sqrt{18 \times 5 \times 5 \times 8 } = {60cm}^{2}$
then make height of triangle
$\frac{1}{2} \times 10 \times h = 60 {cm}^{2}$
h=12cm
area of trapezium=
$\frac{1}{2} \times sum \: of \: parallel \: sides \times height$
area=
$180 {cm}^{2}$