Quick Notes

Quick Notes

Mathematics Chapter 10: Perimeter and Area
10.1 Perimeter
 
10.1  Perimeter
 
Definition

The total length around an enclosed area.
 
Example

Determine the perimeter of the following shape.

\(\begin{aligned} &\space\text{Perimeter} \\\\&=PQ+QR+RS+ST \\&\quad +TU+UV+VW+WP \\\\&=4+3+4+3+4+9 \\&\quad+12+9 \\\\&=48\text{ cm}. \end{aligned}\)
 
Estimate the perimeter accurately:
 

Steps to estimate the perimeter of various shapes.

  1. Trace the shape of the object on a grid of equal squares with sides of \(1\text{ cm}\).
  2. Estimate the perimeter of each shape based on the grid.
  3. Measure the perimeter of each shape using a ruler or a thread.
  4. Record your estimation and measurement.
  5. Compare the estimated value with the measured value to evaluate the accuracy of your estimation.
 
  • The accuracy of estimated perimeter can be evaluated by comparing the estimated value with the measured value.
  • The smaller the difference between the values of estimated perimeter and measured perimeter, the more precise the estimated value.
 
The formulae for the perimeter of various shapes:
 
(i) The perimeter of a triangle
 

 
\(\text{Perimeter}=a+b+c\)
 
(ii) The perimeter of a paralellogram
 

 
\(\text{Perimeter}=2a+2b\)
 
(iii) The perimeter of a kite
 

 
\(\text{Perimeter}=2a+2b\)
 
(iv) The perimeter of a trapezium
 

 
\(\text{Perimeter}=a+b+c+d\)