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

• A. (π)(D)
• B. (0.785)(D²)
• C. (2π)(r)
• D. (π)(r²)

Answer: (B)

The area of a circle is calculated using the formula (π)(r²), where 'r' represents the radius of the circle. This formula arises from the properties of circles and involves squaring the radius and then multiplying by the constant π, which is approximately 3.14159. The radius is the distance from the center of the circle to any point on its circumference.

In this case, while the chosen answer (0.785)(D²) is related to the area, it does not align with the standard formula used in geometry. It appears to incorporate a factor of 0.785, which approximates π/4, but it is not the definitive formula for area. Instead, the area formula should utilize the radius squared rather than diameter. Thus, the correct formula remains (π)(r²) where the radius is half the diameter, showing the relationship between diameter and radius but not substituting one for the other in the area calculation.