Answer
Perimeter of a square $P = 4A$
Circumference of a circle $P = 2\pi r$
Work Step by Step
Example of two variables that vary directly
1) Perimeter of a square, P
P = 4A, where A is length of the side of square
Here we see that they vary directly
2) Similarly circumference of circle
$P = 2\pi r$
Circumference varies directly with the radius
