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How to Calculate the Area of a Circle with a Diameter of 9 cm

Learn how to easily calculate the area of a circle with a 9 cm diameter using the correct formula.

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Video transcript

To find the area of a circle with a diameter of 9 cm, use the formula: Area = πr². First, find the radius by dividing the diameter by 2. So, radius (r) = 9 cm / 2 = 4.5 cm. Then calculate the area: Area = π × (4.5 cm)² ≈ 63.62 cm².

Questions and answers

  1. What is the area of a circle with a radius of 4.5 cm?

    The area is approximately 63.62 cm² using the formula A = πr².

  2. How do you find the diameter from the radius?

    To find the diameter, simply multiply the radius by 2.

  3. What is the formula for calculating the area of a circle?

    The area of a circle is calculated using the formula A = πr², where r is the radius.

  4. Why is π important in circle calculations?

    π (pi) is a constant used in calculations involving circles, representing the ratio of the circumference to the diameter.

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