Measurement of area. Measuring area of regular and irregular shaped objects.
Recap:
In the previous session, we have learnt:
Motivation:
In this session, we will learn about a derived quantity: Area.
------------------------------------
What is area?
Length X Length
Yes.
Width is nothing but a type of length.
Other type of length:
How to measure the area of regular shaped objects?
area = L x W = 5 metre X 4 metre = 20 metre x metre = 20 metre² = 20 m²
The area of regularly shaped figures can be calculated using the relevant formulae.
Diameter = 2 x Radius
2 R = 6
⇒ R = 3
Area = π (R)²
⇒ Area = π (3)²
⇒ Area = 9 π
------------------------------------
How to measure the area of irregular shaped object?
Total number of small squares inside the shaded region = 12
Area of shaded region = 12 x area of small square
area of shaded region = 12 x 1 m² = 12 m²
We use similar technique in calculating area of irregular shaped objects
Watch the below video to learn in detail.
Total squares inside the shaded region = 10
Area of shaded region = 10 x 2 m²
⇒ Area of shaded region = 20 m²
Tip: Think before answering.
In general, how many lengths needs to be measured to measure the area?
Area of irregular shaped object can not be measured.
True or False?
False.
If a rectangle has length = 5 cm, and it has breadth = 5
What is the area?
25
Area of rectangle = Length x Breadth
= 5 x 5
= 25
Count the valid squares inside both the images:
Number of squares inside the irregular shape:
area of 1 square on left = 1 m²
area of 1 square on right = 1/4 m²
Area of left side irregular shape = area of 5 big squares = 5 m²
Area of left side irregular shape = area of 25 small squares = 25/4 m² = 6.25 m²
Conclusion:
As we decrease the area of mesh, we get more approximate result.
Area of circle has different unit than area of square.
True or False?
False.
SI Unit of area is (m²) is same for all the areas.