Question

The area of trapezium is 144.5 sq.cm and it's height is 8.5 cm long. If one of the parallel sides is 20.4 cm long,what is the length of the other side?

Answer 1

Hi ,

Let a and b are the two parallel sides of

the Trapezium ,

a = 20.4 cm

b = ?

height ( h ) = 8.5 cm

area ( A ) = 144.5 square cm

we know that ,

[( a + b ) h ]/ 2 = A

[ ( 20.4 + b ) × 8.5 ] / 2 = 144.5

20.4 + b = ( 144.5 × 2 ) / 8.5

20.4 + b = 289 / 8.5

20.4 + b = 34

b = 34 - 20.4

b = 13.6 cm

Therefore ,

length of the other side = b = 13.6 cm

I hope this helps you.

:)

Answer 2

Height of trapezium(h) = 8.5 cm
One parallel side,a = 20.4 cm
Another parallel side = b cm

Area of trapezium = ½h(a+b)
144.5 = ½(8.5) (20.4+b)
144.5÷½(8.5)= 20.4+b
144.5×2/(8.5) = 20.4+b
17×2 = 20.4+b
34 = 20.4+b
b = 34 - 20.4
b = 13.6

Therefore, the other parallel side is 13.6 cm