11.1 INTRODUCTION
In Class VI, you have already learnt perimeters of plane figures and areas of squares and
rectangles. Perimeter is the distance around a closed figure while area is the part of plane or
region occupied by the closed figure.
In this class, you will learn about perimeters and areas of a few more plane figures.
11.2 SQUARES AND RECTANGLES
Ayush and Deeksha made pictures. Ayush made his picture on a rectangular sheet of length
60 cm and breadth 20 cm while Deeksha made hers on a rectangular sheet of length 40 cm
and breadth 35 cm. Both these pictures have to be separately framed and laminated.
Who has to pay more for framing, if the cost of framing is Rs 3.00 per cm?
If the cost of lamination is Rs 2.00 per cm^2 , who has to pay more for lamination?
For finding the cost of framing, we need to find perimeter and then multiply it by the rate
for framing. For finding the cost of lamination, we need to find area and then multiply it by the
rate for lamination.
What would you need to find, area or perimeter, to answer the following?- How much space does a blackboard occupy?
- What is the length of a wire required to fence a rectangular flower bed?
- What distance would you cover by taking two rounds of a triangular park?
- How much plastic sheet do you need to cover a rectangular swimming pool?
Do you remember,
Perimeter of a regular polygon = number of sides × length of one side
Perimeter of a square = 4 × side
Chapter 11 Perimeter and Area
TRY THESE