4a. Find the radius of a circle with an area of 1,809.56 square centimeters. How did you calculate it?

A = πr2


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(2 points)

1 answer

To find the radius of a circle given its area, we can use the formula for the area of a circle:

\[ A = \pi r^2 \]

Where:

  • \( A \) is the area of the circle.
  • \( r \) is the radius of the circle.
  • \( \pi \) (pi) is approximately 3.14159.

Given that the area \( A = 1,809.56 \) square centimeters, we can rearrange the formula to solve for the radius \( r \):

  1. Start with the area formula:

\[ A = \pi r^2 \]

  1. Substitute the known area into the equation:

\[ 1,809.56 = \pi r^2 \]

  1. To isolate \( r^2 \), divide both sides by \( \pi \):

\[ r^2 = \frac{1,809.56}{\pi} \]

  1. Now, using \( \pi \approx 3.14159 \):

\[ r^2 = \frac{1,809.56}{3.14159} \]

  1. Calculate the right side:

\[ r^2 \approx \frac{1,809.56}{3.14159} \approx 576.00 \]

  1. Now, take the square root of both sides to find \( r \):

\[ r = \sqrt{576.00} \]

  1. Calculate the square root:

\[ r \approx 24.00 \text{ cm} \]

Thus, the radius of the circle is approximately 24.00 centimeters.

Final Answer:

Radius = 24.00 cm.