The Lesson

The area of a circle is found using the formula:
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In this formula, d is the diameter the the circle. The image below shows what we mean by diameter:
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Interactive Widget

Use this interactive widget to attract a circle and also then calculation its area from the diameter. Start by clicking in the shaded area.

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How to find the Area that a Circle making use of the Diameter

Finding the area of a circle utilizing the diameter is easy.

Question

What is the area of a circle v a diameter of 10 cm, as presented below?
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Area = π × 102⁄4

Area = π × 10 × 10 ÷ 4

Area = π × 100 ÷ 4

Area = π × 25

Area = 3.14 × 25

Area = 78.5 cm2


Lesson Slides

The slider listed below shows another real instance of how to find the area of a circle utilizing the diameter.Open the slider in a new tab

How to discover the Area the a Circle using the Radius

The area of a circle have the right to be discovered using the radius rather than the diameter.The area that a circle, making use of the radius, is discovered using the formula:
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In the formula, r is the radius of the circle. The image below shows what we mean by radius:
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Read more about exactly how to find the area of a circle using the radius

What Is a Circle?

A circle is a shape containing a collection of points that room all the exact same distance from a given point, that center.

Why does This Formula Work?

The formula because that the area the a circle is far better known in terms of the radius:
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The radius can be found from the diameter. The radius is fifty percent the size of the diameter:
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Substitute d⁄2 because that r:
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The d⁄2 in the base is being squared. When a portion is squared, both the numerator and also the denominator are squared:
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This is is formula for the area the a circle making use of the diameter.

A keep in mind on Units

The area the a one is a size times a length, so us say its measurement is length2. (All locations are lengths squared).This affects the systems used. If the diameter is in cm, the area is in cm2. If that is in inches, the area is in inches2.

See more: All-Purpose Flour Chemical Formula For Wheat Flour? What Is The Chemical Formula For Wheat Flour


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See Also

What is a circle?What is pi?What is the diameter?Find the area the a circle utilizing the radiusHow to uncover the radius from the diameterThe exponent where the base is a fractionWhat is the numerator?What is the denominator?

The Test

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