How to find circumference and area

To find circumference starting with the radius then diameter you have to know these math equations

c=2(pi)r d=2r if the radius is 4 cm what is the circumference?

i will show what i know

r=4 so you times raduis by 2 and it will look like this (4)r X 2=8 the answer is the diameter so now you should know this pi is 3.14 when you are finding the radius you need to multiply it by pi so it will look like
(you need a calculator) 8 X 3.14= 25.1 the real answer is 25.12 but i used the up to tenths

To find circumference starting with the diameter you need to know just one math equation
c=(pi)d
for this you also need a calculator if the diameter is 12 what is the circumference?

To find this you just divide the diameter by pi<======= so it looks like this 12 \ 3.14=3.8

Again I use only the tenths place value

To find area using diameter

to find the area of the circle you basically multiply the diameter by 3 so if the diameter is 8 thern you multiply it by 3 it equals 24

and thats all I know