Because it was found that there was a direct relationship between the radii (or diameters) of circles and their circumferences.
Archimedes, a famous Greek mathematician, born about 287 B.C.
There is no circumference of a cone, but, we only do the circumference of the circle. the formula for the circle is pi times D. D= Diameter
Circumference of a circle is (pi * diameter). Area of a circle is (pi * r2).
The formula for the circumference of a circle is pi * diameter or (2 radius.)
Circumference of a circle = (pi) x (diameter)
2r+pi r
PI times the DIAMETER
2*pi*radius = perimeter or circumference of a circle radius = circumference/2*pi
It is the formula for finding the circumference of a circle which is the same as 2*pi*radius
Divide the circumference by 2*pi because 2*pi*radius = circumference
The formula for finding the circumference of a circle is:-circumference of a circle = pi * the diameter of circlewhere The value of pi is approximately 3.14thus the circumference = 3.14*1.5 = 4.71 meters
pi x 2r