Question

Area of trapezium is 140 cm² Its height is 10 cm. Difference between parallel sides is 4 cm. Find the lengths of both parallel sides.

Answer 1

Let a cm. and b cm. be the lengths of parallel sides where a > b.

Area of trapezium = 1/2 x (Sum of parallel sides) x height

⇒ 140 = 1/2(a + b) 10

⇒ 140 x 2 = (a + b) 10

⇒ 280 = (a + b) 10

⇒ a + b = 280/10

⇒ a + b = 28 …(1)

Again, a – b = 4 …(2)

Adding (1) and (2)

2 a = 32

⇒ a = 32/2 = 16 cm.

Putting a = 16 in (1)

16 + b = 28

⇒ b = 28 – 16

⇒ b = 12 cm.

Hence, the required lengths of parallel sides are 16 cm. and 13 cm. respectively.