The circumference is a figure that has a circular shape and is present in many situations related to our daily lives. If we look closely around us, we can see that the circular shape is very important for the perfect functioning of some objects. For example, the wheels of a car have a circular shape, which makes it easier to move around. Another part of the car with the shape of a circle is the steering wheel, which has this shape for better steering control of the car.
The wheels of a bicycle, the lid of a pot, some traffic signs, among other objects, have a circular shape.
In sport we also observe the presence of the circular shape. The center of the soccer field and a futsal court is delimited by a circumference. Some people confuse circumference with circle, but the difference between the two is very easy to establish. Look:
The circle is the inner part of the circumference.
The circumference is the line that borders the circle.
All other flat geometric shapes have width and length measurements, which are used in calculating the area of these figures. In the case of the circle, the element responsible for its area is called the radius, which is determined by the distance from the center of the circle to the edge.
The area of a circular region is calculated by the expression, where r is the radius measure and π is a Greek letter of fixed value equal to 3.14.
Example 1
Let's calculate the area of a circular region with a radius measuring 10 meters.
A = 3.14 * 10²
A = 3.14 * 100
A = 314 m²
As we are working with area, the unit of measurement should be the square meter.
Example 2
A square has a circular shape with a radius measuring 20 meters. Calculate how many square meters of grass are needed to fill this square.
A = 3.14 * 20²
A = 3.14 * 400
A = 1,256 m²
by Mark Noah
Mathematical
Related video lesson:
