The length of a rectangle is 15 cm and breadth is 8 cm. If the length is increased by 5 cm and breadth is increased by 2 cm, then the increase in area is equal to
The correct option is B: 80 cm2
Let ABCD be the rectangle with AB=15 cm and CB=8 cm.
Let the length and breadth be increased by 5 cm and 2 cm respectively as shown.
Area of original rectangle ABCD=15×8 cm2
Area of new rectangle AEGI will be
area ABCD+ area DCFE+ area CHGF+ area BIHC
=(15×8)+(2×15)+(2×5)+(8×5)
Hence, increase in area = area of rectangle AEGI− Area of rectangle ABCD
=[area ABCD+ area DCFE+ area CHGF+ area BIHC] - area ABCD
= area DCFE+ area CHGF+ area BIHC
=(2×15)+(2×5)+(8×5)
=30+10+40
=80 cm2