Acircle has a diameter of 9 cm. find the circumference. give a simplified exact answer. enter pi with answer. for example 4pi

Circumference = Diameter *

So 9 is the answer

First, find the radius of the circle. 
-The radius of a circle is half the length of the diameter. If r=radius and d=diameter it would be r=d/2. The radius of the circle is r=9/2=4.5. So the radius of the circle is 4.5 cm. 

Second, use the circumference equation of a circle to find the circumference. 
The equation is C=2r, where C=circumference and r=radius. Then plug in your numbers. 
C=24.5=9

So the answer is 9 cm.