CIRCUMFERENCE OF A CIRCLE
Another term of Perimeter of a circle is known as circumference of a circle. This page is going to guide you how to find the perimeter of a circle.
Formula :
Circumference of circle = 2 Π r
Here the value of Π is either 22/7 or 3.14 and "r" stands for radius of a circle.
Here the length of the red line is known as circumference of a circle. Now let us see some example problems to understand this topic better.
Example 1:
Find the circumference of a circle whose radius is 14 cm.
Solution:
To find the circumference of circle we need to use the formula to find the circumference of circle.
Circumference of circle = 2 Πr
= 2 ⋅ (22/7) ⋅ 14
= 2 ⋅ 22 ⋅ 2
= 4 ⋅ 22
= 8 cm
Example 2:
Find the diameter of circle whose circumference is 42 cm.
Solution:
Circumference of circle = 42 cm
2 Π r = 42
2 ⋅ (22/7) ⋅ r = 42
r = (42 ⋅ 7) / (2 ⋅ 22)
r = 294/44
r = 6.68 cm
Now we have to find the diameter for that we have to multiply the radius by 2.
Diameter = 2 r
= 2(6.68)
= 13.36 cm
Example 3:
A moon is about 384000 km away from the earth and its path around the earth is nearly circular. Find the distance traveled by moon every month.
Solution :
In one month, the moon describes a full circle about the earth.
Now the circumference = 2 Π r
= 2 ⋅ (22/7) ⋅ 384000 km
= 2413714 km
Hence the distance traveled by the moon = 2413714 km
Example 4 :
A copper wire is in the form of a circle with radius 35 cm. It is bent into a square. Determine the side of the square.
Solution :
Given: Radius of a circle, r = 35 cm.
Since the same wire is bent into the form of a square,
Perimeter of the circle = Perimeter of the square
Perimeter of the circle = 2Πr units
= 2 ⋅ (22/7) ⋅ 35
P = 220 cm
Let ‘a’ be the side of a square.
Perimeter of a square = 4a units
4a = 220
a = 55 cm
Side of the square = 55 cm.
After having gone through the stuff above, we hope that the students would have understood circumference of a circle.
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