The formula for the area of a circle is determined based on the radius of the circle and involves the constant π (pi). The radius (r) is the distance from the center of the circle to any point on its circumference.
To find the area (A) of a circle, you use the formula:
[tex]\[ A = \pi r^2 \][/tex]
This means you take the radius, multiply it by itself (which gives you [tex]\( r^2 \)[/tex]), and then multiply that result by π.
The correct choice is:
[tex]\[ \boxed{D} \, A = \pi r^2 \][/tex]
