C= 2*pi*r pi= approx. 3.14 So The first one with the radius being 18 would be approximately 113.04 BECAUSE 18 * 2 = 36 36*3.14= 113.04 DO THE SAME PROCESS with the other values you were given...
Also if they give you the diameter the formula is C= d*pi that formula is the same as c=2*pi*r ..... Use either... just remember when they give you the radius.... the radius is half of the diameter... so take the radius times 2 and times that by pi When it asked for an approximation use 3.14 for pi. I'm sure you can do the rest by yourself. I hope this helped!
