Question

The area of a trapezium is 2400 sq.cm and the sum of the parallel sides is three times the height. If one of the parallel sides is 40cm, then the other side length in cm is ________.
1. 120 cm
2. 40 cm
3. 80 cm
4. 60  cm

Answer 1

Correct Answer - Option 3 : 80 cm

Given :

The area of a trapezium is 2400 sq.cm and the sum of the parallel sides is three times the height and one of the parallel sides is 40cm.

Concept used :

Area of  a trapezium = (1/2) × (sum of parallel sides) × Height 

Calculations :

Let the length of other side be 'l' cm 

40 + l = 3 × Height 

Height = (40 + l)/3

Area of trapezium = (1/2) × (40 + l) × (40 + l)/(3) 

(40 + l)² = 2400 × 2 × 3 

⇒ (40 + l)² = 14400

⇒ 40 + l = √14400 

⇒ l + 40 = 120 

⇒ l = 80 

∴ Option 3 will be the correct answer.