what is the area of a circle if its diameter is 9 centimeters
A=pi·r²
r being radius
if the diameter is 9 you have to divide it by 2 to get r
r=4.5
A=pi(3.14)·4.5
A≈14.13 ( I use the ≈ because pi is irrational and goes on forever but = works too)
So the area is 14.13 units