Question

The length of a rectangle is 12 cm and its breadth is 6 cm. If the length is increased by 4 cm, the increase in area is equal to

• A. $26c{m}^2$
• B. $24c{m}^2$
• C. $22c{m}^2$
• D. $18c{m}^2$

Answer 1

The correct option is B

$24c{m}^2$

Let ABCD be the rectangle with AB = 12 cm and CB = 6 cm

Let length be increased by 4 cm,

BF = 4cm, AF = (12 + 4)cm

Area of original rectangle ABCD = $12\times 6c{m}^2$

Area of new rectangle AFED = $(12+4)\times 6c{m}^2$

$=12\times 6+4\times 6$

Hence, increase in area is $4\times 6=24c{m}^2$