Area of the trapezium =500cm2
Distance between the parallel sides of the trapezium =10cm
Ratio of the lengths of the parallel sides of the trapezium =4:1
Let the lengths of the parallel sides of the trapezium be 4x and xcm.
Area of the trapezium =12(a+b)×h
⇒500=12(x+4x)×10
⇒500=(x+4x)5
⇒500=25x
⇒x=50025=20cm
∴ One parallel side =20cm
∴ The other parallel side =4x=4×20=80cm (∵ parallel sides are in 4:1)