To find the area of a circle in terms of π, you can use the formula:
\[ A = \pi r^2 \]
where \( A \) is the area and \( r \) is the radius of the circle.
Given the diameter of the circle is 18 cm, we can find the radius \( r \) by dividing the diameter by 2:
\[ r = \frac{18 \, \text{cm}}{2} = 9 \, \text{cm} \]
Now, substitute the radius back into the area formula:
\[ A = \pi (9 \, \text{cm})^2 \]
\[ A = \pi (81 \, \text{cm}^2) \]
\[ A = 81\pi \, \text{cm}^2 \]
Therefore, the area of the circle in terms of π is:
\[ 81\pi \, \text{cm}^2 \]
So, the correct answer is:
\[ 81\pi \, \text{cm}^2 \]
6.
The diameter of a circle is 18 cm. What is its area in terms of π.
324π cm2
18π cm2
180π cm2
81π cm2
1 answer