If the diameter of a circle is 10 units, what is its area?

To determine the area of a circle, we use the formula:

[

\text{Area} = \pi r^2

]

where ( r ) is the radius of the circle. Given that the diameter of the circle is 10 units, we first need to find the radius. The radius is half of the diameter:

[

r = \frac{\text{diameter}}{2} = \frac{10}{2} = 5 \text{ units}

]

Now we can substitute the radius back into the area formula:

[

\text{Area} = \pi (5)^2 = \pi \times 25 = 25\pi \text{ square units}

]

Thus, the area of the circle is indeed ( 25\pi ) square units, confirming that the answer is correct. This calculation accurately reflects the relationship between the diameter and the radius and applies the area formula for a circle correctly.