Calculate the area of circles

The area of a circle is the amount of planar surface enclosed by its circumference, calculated as $A=\pi r^2$ , where $r$ is the radius; given a diameter, the radius must first be found by halving it. Results may be expressed exactly using $\pi$ or approximated with an appropriate value of $\pi$ , in square units, without extending to sectors, radians, or calculus-based formulas.

Detailed Explanation: Calculate the area of circles

To find the area of a circle, use the formula

A=\pi r^2

where $r$ is the radius. The radius is the distance from the center of the circle to its edge.

If you are given the diameter, divide it by $2$ to find the radius.

Example: Find the area of a circle with a diameter of $12\text{ cm}$ .

Find the radius:

r=\frac{12}{2}=6\text{ cm}

Substitute the radius into the area formula:

A=\pi(6)^2

Square the radius:

A=36\pi\text{ cm}^2

This is the exact area. Using $\pi\approx 3.14$ :

A\approx 36(3.14)=113.04\text{ cm}^2

The area is $\boxed{36\pi\text{ cm}^2}$ , or approximately $\boxed{113.04\text{ cm}^2}$ .

Learn by doing: Calculate the area of circles

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Area of a Circle from Diameter - To Pi Value

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Calculate the area of circles

Detailed Explanation: Calculate the area of circles

Learn by doing: Calculate the area of circles

Practice with unlimited practice problems

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Area of a Circle from Diameter - To Pi Value