Question

the diameter of a circle is 18 kilometers. what is the area? d = 18 km give the exact answer in simplest form. square kilometers

Explanation:

Step1: Find the radius

The radius $r$ of a circle is half of the diameter $d$. Given $d = 18$ km, so $r=\frac{d}{2}=\frac{18}{2}=9$ km.

Step2: Calculate the area

The area formula of a circle is $A=\pi r^{2}$. Substitute $r = 9$ km into the formula, we get $A=\pi\times9^{2}=81\pi$ square - kilometers.

Answer:

$81\pi$