Question

if a circle of radius 2 is made to roll along the x-axis, what is an equation for the path of the center of the circle?

Answer 1

It would be 2 height above the x axis
it would be y=2

Answer 2

The area of the circle is equal to pi multiplied by the square of the radius. the general equation that represents the equation of the circle is x^2  + y^2 = r^2. r is equal to 2 such that r^2 is equal to 4. hence the equation becomes
x^2  + y^2 = 4