Question

A strip, 2 cm broad, along the sides of a sheet of paper which is 20 cm long and 10 cm broad, has been coloured. What is the area of the coloured part?

Answer 1

Let PQRS be the sheet of paper that has a strip along it measuring 2 cm. From the given information, we get the figure ABCD that is also a rectangle.
Length of PQRS = 20 cm
Breadth of PQRS = 10 cm
Area of PQRS = length × breadth
= 20 × 10 cm²
= 200 cm²
Now, there is a strip measuring 2 cm along the sheet.
∴ Length of ABCD = 20 − 2 − 2 cm = 16 cm
Breadth of ABCD = 10 − 2 − 2 = 6 cm
Area of ABCD = length × breadth
= 16 × 6 cm²
= 96 cm²
Area of the coloured part = Area of PQRS − Area of ABCD
= 200 cm² − 96 cm²
= 104 cm²