Question

The parallel sides of a trapezium are in the ratio 3:5 and the height between the parallel sides is 10cm.If the bigger of the parallel sides is 30cm, find the area of the trapezium.

Answer 1

`A=240\ cm^2`

Explanation:

Let

x -----> one parallel side of the trapezium

y ----> the other parallel side of the trapezium (bigger side)

we know that

The area of the trapezium is equal to

`A=(1)/(2)(x+y)h` ----> equation A

`(x)/(y)=(3)/(5)` ---->
`x=(3)/(5)y` ---> equation B

we have

`h=10\ cm\\y=30\ cm`

Find the value of x

substitute the value of y in the equation B

`x=(3)/(5)(30)=18\ cm`

Find the area

substitute the values in the formula

`A=(1)/(2)(18+30)10`

`A=240\ cm^2`