area of circle

What is the formula for the area of a circle?

The formula is A = \pi r^2, where A is the area and r is the radius of the circle.

What does the radius (r) represent in the area formula?

The radius is the distance from the center of the circle to any point on its outer edge.

How is the radius (r) related to the diameter (d)?

The radius is half of the diameter, or r = \frac{d}{2}. To find the area from the diameter, you must first divide the diameter by 2.

What numerical value is commonly used for \pi?

\pi (pi) is an irrational number approximately equal to 3.14159, though 3.14 or the fraction \frac{22}{7} are often used for simplicity.

If a circle has a radius of 4 cm, what is its area?

Using A = \pi r^2, the area is A = \pi \times 4^2 = 16\pi, which is approximately 50.27 cm^2.