Question

The length of a rectangle is 12cm and its breadth is 8 cm. If the length is increased by 3 cm, then the increase in area is equal to

• A. $2.18c{m}^2$
• B. $21c{m}^2$
• C. $24c{m}^2$
• D. $27c{m}^2$

Answer 1

The correct option is C

$24c{m}^2$

Let ABCD be the rectangle with AB = 12 cm and CB = 8 cm

Let length be increased by 3 cm,

BF = 3cm, AF = (12 + 3)cm

Area of original rectangle ABCD = $12\times 8c{m}^2$

Area of new rectangle AFED = $(12+3)\times 8c{m}^2$

$=12\times 8+3\times 8$

Hence, increase in area is $3\times 8=24c{m}^2$