Final answer:
To find the value of r in the equation for the area of a circle, divide the area by π and take the square root.
Step-by-step explanation:
To find the value of r in the equation for the area of a circle, we can use the formula A = πr². Given that the area of circle Z is 64π ft², we can set up the equation as 64π = πr². To solve for r, we divide both sides of the equation by π and then take the square root of both sides. This gives us r = 8 ft.