If you double the length of the radius of a circle, what effect does it have on: the circumference of the circle, and the area of the circle?

you!

No effect bc it just gives you the diameter

C=2pir

when r is replaced with 2r
cnew=2pi2r
cnew=2(2pir)
cnew=2(c)

it is doubling the original circumference

area
area=pir^2
r to 2r
areanwe=pi(2r)^2
areanew=pi(4r^2)
areanew=4pir^2
areanew=4area
it is 4 times of original area

the result is that the circumference is doubled and area is multiplied by 4