The image above is a circle.
To compute the perimeter or circumference of a circle, one essential parameter is needed and this parameter is the radius of a circle (r). You can also use the diameter of a circle to compute the area of a circle (d).
The formula for calculating the perimeter or circumference of a circle is:
P = 2πr
Where:
P = Perimeter or Circumference of a circle
r = Radius of a circle
Let’s solve an example:
Find the perimeter or circumference of a circle where the radius of a circle is 8 cm.
This implies that;
r = Radius of a circle = 8 cm
P = 2πr
P = 2 x 3.142 x 8
P = 50.265
Therefore, the perimeter or circumference of a circle is 50.265 cm.
Calculating the Area of a Circle using the Diameter of a Circle.
The formula is P = πd
Where:
P = Perimeter or Circumference of a circle
d = Diameter of a circle
Let’s solve an example:
Find the perimeter or circumference of a circle where the diameter of a circle is 10 cm.
This implies that;
d = Diameter of a circle = 10 cm
P = πd
P = 3.142 x 10
P = 31.42
Therefore, the perimeter or circumference of a circle with diameter is 31.42 cm.
How to Calculate Radius of a Circle when Perimeter or Circumference of the Circle is Given
r = P / 2π
where;
r = Radius of a circle
P = Perimeter or Circumference of a circle
Let’s solve an example:
Find the radius of a circle where the perimeter or circumference of the circle is 16 cm.
This implies that;
P = Perimeter or Circumference of the circle = 16 cm
r = P / 2π
r = 16 / 6.284
r = 2.55
Therefore, the radius of the circle is 2.55 cm.
How to Calculate Diameter of a Circle when Perimeter or Circumference of the Circle is Given
d = P / π
where;
d = Diameter of a circle
P = Perimeter or Circumference of a circle
Let’s solve an example;
Find the diameter of a circle where the perimeter or circumference of the circle is 20 cm
This implies that;
P = Perimeter or Circumference of the circle = 20 cm
d = P / π
d = 20 / π
d = 6.365
Therefore, the diameter of the circle is 6.365 cm.