Summarize this article:
Last updated on September 17, 2025
The area of a circle is the space contained within its circumference. There are specific formulas for calculating the area of circles, which are essential in fields like engineering and design. In this section, we will explore how to calculate the area of a circle using its circumference.
The circumference of a circle is the distance around the circle. The area is the total space enclosed within this boundary.
The relationship between the circumference and the area of a circle is a fundamental concept in geometry.
To find the area of a circle using its circumference, we use the formula: Area = C² / (4π), where C is the circumference of the circle. Now let's see how this formula is derived.
Derivation of the formula: The circumference of a circle is given by C = 2πr, where r is the radius. The area of a circle is given by A = πr². Substituting the expression for r from the circumference formula, r = C / (2π), into the area formula gives: A = π(C / (2π))² = C² / (4π). Therefore, the area of the circle in terms of its circumference is A = C² / (4π).
We can find the area of a circle using its circumference by applying the derived formula. The process involves a simple substitution of the circumference value into the formula.
Here's how you can calculate it: For example, if the circumference of a circle is 31.4 cm, what is its area? Area = C² / (4π) = (31.4)² / (4 × 3.14) ≈ 78.5 cm² The area of the circle is approximately 78.5 cm².
The area of a circle is measured in square units. The specific unit depends on the measurement system used:
In the metric system, the area is measured in square meters (m²), square centimeters (cm²), and square millimeters (mm²).
In the imperial system, the area is measured in square inches (in²), square feet (ft²), and square yards (yd²).
The area of a circle can be determined through its radius, diameter, or circumference. Here are some special scenarios:
Case 1: Using Circumference If the circumference is given, use the formula Area = C² / (4π).
Case 2: Using Radius If the radius is given, the area is calculated using A = πr².
Case 3: Using Diameter If the diameter is given, the area is calculated using A = π(d/2)².
Here are some tips to ensure accurate calculations when determining the area of a circle: The diameter is twice the radius.
Remember that the circumference is the total distance around the circle, whereas the area is the space it encloses. Using the formula Area = C² / (4π) is helpful when only the circumference is known. Convert all measurements to the same unit before calculating the area.
Common mistakes occur when finding the area of a circle. Here are some to watch out for:
A circular pond has a circumference of 62.8 m. What is the area?
We will find the area as approximately 314 m².
Given the circumference C = 62.8 m, we use the formula
Area = C² / (4π).
Area = (62.8)² / (4 × 3.14) ≈ 314 m².
What will be the area of a circular garden if its circumference is 25.12 cm?
We will find the area as approximately 50.24 cm².
With a circumference of 25.12 cm, use
Area = C² / (4π).
Area = (25.12)² / (4 × 3.14) ≈ 50.24 cm².
A circular field has an area of 706.86 m². What is its circumference?
We find the circumference as approximately 94.2 m.
Given the area A = 706.86 m², first find the radius using A = πr², then find the circumference C = 2πr.
Find the area of a circle with a circumference of 21.98 cm.
We will find the area as approximately 38.5 cm².
Given C = 21.98 cm, use the formula
Area = C² / (4π).
Area = (21.98)² / (4 × 3.14) ≈ 38.5 cm².
Help Sarah find the area of a circle if its circumference is 44 m.
We will find the area as approximately 154 m².
Given the circumference C = 44 m, use the formula
Area = C² / (4π).
Area = (44)² / (4 × 3.14) ≈ 154 m².
Seyed Ali Fathima S a math expert with nearly 5 years of experience as a math teacher. From an engineer to a math teacher, shows her passion for math and teaching. She is a calculator queen, who loves tables and she turns tables to puzzles and songs.
: She has songs for each table which helps her to remember the tables