To find the area of the circle with diameter = 18 cm
We will use the formula:
![\text{Area of a cirlce = }\pi r^2](https://img.qammunity.org/2023/formulas/mathematics/college/mcvr6ymkvvot7icf80ns28zg3hf1aai4av.png)
where r= radius of the circle
From the quesion diameter = 18 cm
radius = diameter/2
radius = 18cm/2 = 9 cm
substituting r = 9cm into the formula
![Area\text{ of a circle = }\pi(9)^2](https://img.qammunity.org/2023/formulas/mathematics/college/mqyuzce2odliwos6ugcoum3d4hw1s7fvfl.png)
![A\text{rea of the circle }=\text{ 81}\pi cm^2](https://img.qammunity.org/2023/formulas/mathematics/college/s4yb2xovkm0ume5szragxkb6ivsgf9syjg.png)
The above answer is when we are to leave the answer in terms of π
Otherwise if π is given to be 3.14 or 22/7 , we will simply substitute into the formula
That is given that π= 3.14
![\text{Area of the circle = 81 }*3.14=254.34cm^2](https://img.qammunity.org/2023/formulas/mathematics/college/u8z6493mkkisnc2k6zxcti2qxkz4xrxviq.png)