Which equation gives the area of a circle?

Which equation gives the area of a circle?

• A. A = π r²
• B. C = 2πr
• C. V = π r^2
• D. E = π d

Answer: (A)

Area of a circle is π times the radius squared. That means the circle’s area grows with the square of the radius, scaled by π. The radius is the distance from the center to the edge, so squaring it accounts for how much area is covered as you enlarge the circle. The other expressions describe different quantities or are incomplete: the circumference around a circle is 2πr, not area; V = π r^2 isn’t a standard, complete volume formula for common solids (a sphere uses (4/3)π r^3); and if you want area in terms of diameter, you’d use A = π(d/2)^2 = (π d^2)/4, not π d. So the formula A = π r^2 is the correct way to compute the area using the radius.

Area of a circle is π times the radius squared. That means the circle’s area grows with the square of the radius, scaled by π. The radius is the distance from the center to the edge, so squaring it accounts for how much area is covered as you enlarge the circle.

The other expressions describe different quantities or are incomplete: the circumference around a circle is 2πr, not area; V = π r^2 isn’t a standard, complete volume formula for common solids (a sphere uses (4/3)π r^3); and if you want area in terms of diameter, you’d use A = π(d/2)^2 = (π d^2)/4, not π d.

So the formula A = π r^2 is the correct way to compute the area using the radius.