Applications Of Area of a Circle In Daily Life

Where area of a circle applies in daily life? 

Almost everywhere!

Look at the shapes (shapes of objects) all around us. An object with a circular face such as a dinning plate, a pop can, a traffic cone or a circular flower bed in a garden are all built or prepared keeping the concept of area of a circle in mind. Following are the main objects (three dimensional shapes) where the area of a circle is used and all such objects used in our day to day lives:

1) Finding the volume and surface area of a cylinder:  A cylinder is  a 3D object with two circular faces and one curved surface. For example a popcan is a very good example of cylinder. Now if we want to know how much metal sheet is required to build this popcan, it can't be accomplished without finding the area of two circular faces. Similarly, if we want to find out how much coke this can will hold (called volume of the can), it can't be calculated without the knowledge of area of a circle. 

When it comes to finding the surface area (how many square units of metal sheet needed to make the popcan) and volume (how much liquid this popcan will hold), area of a circle is the key to develop the formulas. 

Remember; Area of any solid (or 3D object) is the sum of areas of all of its faces and Volume is the area of base times its height

Let's start with the cylinder given below

We need the radius of the circular lids of the cylinder alongside with its height (length). Then its surface area and volume can be calculated using the following formulas:

Where “r” is the radius of the cylinder and “h” is its height. Remember that; there are only two parameters to find the surface area or volume of any cylindrical shape which are; number one "radius of the circular face" and number two "its height".

2)  Surface area and volume of a cone: Cone is another very  important three dimensional shape and students need to know how to find  its surface area and volume. Again, the area of a circle formula is the key. 

Given in the above image a right circular cone with the radius of “r”,  slant height “s” and the perpendicular height “h”. Now we can find the  surface area and volume of this cone as shown below: 

Note that we need three parameters to find the surface area and volume of a cone; radius of the circular face, its perpendicular height and its slant height. Also the volume of the cone is one third the volume of the cylinder with same radius and perpendicular height.

3)  Surface area and volume of a sphere: The sphere is another  very important three dimensional shape. A soccer ball and shot-put are the perfect  examples of a sphere. Area of the circle is again the base to find the  surface area and volume of a sphere or a semi-sphere such as a dinner bowl:

We can find the surface area and volume of above sphere by using the formulas as shown below:

Please note that for a sphere we need only one perimeter which is its radius, to find both its surface area and volume. Hence it is very easy to work on problems finding surface area and volume of a sphere or a semi-sphere. In contrast cone is hardest to work with as we need to know its radius, perpendicular height and curved (slant) height and cylinder is in the middle.

Hope that above presentation will help the students to understand the applications of area of a circle and also convince them to study math as it applies everywhere in our daily lives.