Question

4th Question Please......

Answer 1

Solution (i) :-

given:

• ar (trapezium) = 12 cm²

• height of trapezium, h = x  

• AD = CD = x
• AB = x + 4

to prove :

we have to prove that

x satisfies x² + 2 x - 12 = 0

proof :

ar (trapezium) = 1/2 * h * (sum of parallel sides)

12 = 1 / 2 * x * ( x + x + 4 )

24 = 2 x² + 4 x

2 x² + 4 x - 24 = 0

x² + 2 x - 12 = 0  ( proVed).

Solution (ii) :-

we have to solve

x² + 2 x - 12 = 0 by completing the square method.

so,

x² + 2 x -12 =0

x² + 2 (x) (1) + 1 - 13 = 0

(x² + 2 (x) (1) + (1)² ) = 13

( x + 1 )² = 13

x + 1 = √13

x = √13  - 1  

x = 3.6 - 1

x = 2.6    (Ans.)