To find the area of a circle, you use the formula:
Area=π×r2\text{Area}=\pi \times r^2Area=π×r2
where rrr is the radius of the circle and π\pi π (pi) is approximately 3.14 or 227\frac{22}{7}722
Steps to find the area of a circle:
- Determine the radius rrr of the circle. If you have the diameter ddd, divide it by 2 to get the radius: r=d2r=\frac{d}{2}r=2d
- Square the radius: r2r^2r2.
- Multiply the squared radius by π\pi π: πr2\pi r^2πr2.
- The result is the area of the circle, expressed in square units (e.g., cm², m²)
Alternative formulas:
- Using diameter directly:
Area=π×(d2)2=πd24\text{Area}=\pi \times \left(\frac{d}{2}\right)^2=\frac{\pi d^2}{4}Area=π×(2d)2=4πd2
- Using circumference CCC:
Area=C24π\text{Area}=\frac{C^2}{4\pi}Area=4πC2
where C=2πrC=2\pi rC=2πr
Example:
If a circle has a diameter of 40 cm, the radius is 202020 cm. The area is:
π×202=3.14×400=1256 cm2\pi \times 20^2=3.14\times 400=1256\text{ cm}^2π×202=3.14×400=1256 cm2
rounded as needed
. This formula applies universally to calculate the area inside any circle.
