To find the area of a circle, you can use the formula:
\[ \text{Area} = \pi r^2 \]
where \( r \) is the radius of the circle. The diameter is given as 10 millimeters, so the radius \( r \) is half of that:
\[ r = \frac{10}{2} = 5 \text{ millimeters} \]
Now, using \( \pi \approx 3.14 \):
\[ \text{Area} = 3.14 \times (5)^2 \]
Calculating \( (5)^2 \):
\[ (5)^2 = 25 \]
Now substituting this back into the area formula:
\[ \text{Area} = 3.14 \times 25 \]
Calculating it:
\[ 3.14 \times 25 = 78.5 \]
Rounding this to the tenths place, we get 78.5, which is approximately 78.8.
Thus, the closest answer choice for the area of the circle is:
B. 78.8
1 answer