# How to measure the circumference of a circle

Eratosthenes
was the first person who measures the circumference of Earth. He was a Greek
mathematician, in 240 B.C. He discovered that objects in a city on the Northern
Tropic don’t throw a shadow at noon on the summer solstice, but they do in a
more northerly location. By knowing this and the length between the locations, he
succeeded in measuring the Earth's circumference. The distance between the two
cities was measured by Eratosthenes to be 800 kilometers. He multiplied 800
kilometers by 50 to arrive at a figure of 40,000 kilometers for the Earth's
diameter.

Even
though the circumference of the circle is its length, it cannot be measured
using a scale like other shapes like squares, triangles and rectangles can the
rationale for this is the circle's bent shape.

The
strategies below can be used to measure the circumference of a circle

**Method
1. We
would use this thread to trace the course of the circle and designate the
places on the trend a common Ruler can be used to check the thread length
later. Study the possibility when we are given a circular plate with a
circumference of a circle. **

Step
1. Using the method described above, we could now take a thread and wrap it
towards the circular plate.

Step 2. Next, on the thread, make a starting
and ending point.

Step 3. Finally, using the perimeter measurement, measure the length of the thread from start to finish point.

**Method
2.****
Measuring the circumference of a circle is an accurate way to calculate it in
geometry. As a result, we apply a formula that involves the radius, diameter of
a circle, and the value of Pi(π) to determine the circumference of a circle. To
the beginning, if we are given the radius and circumference must be computed,
the steps to follow are as follows:**

If the radius of any random circle is 7 cm, we
may determine the circumference using the following steps:

Step 1. Check over the data which have been
provided to us; in this case, the radius has been provided.

Step
2. Use the following formula

C=2πr

Here C = circumferences, r= radius, and π=22/7.

Step
3. We obtain the desired outcomes by substituting values in the formula

Step
4:

C=2π
r=2

Similarly,
if the diameter is specified, we can follow the procedure below:

**Example****:
If the diameter of circular CD is given as 14cm and the circumference is
required, the following is the solution:**

Step
1. Check the given information, in this case, diameter is given.

Step
2.Use the following formula

C=π

(Here,
C denotes circumference, d denotes diameter, and π=22/7 or 3.14)

Step
3.We get the required result by substituting the values in the formula.

C=π