What is the area in square feet of a cylinder that has a radius of 6 inches and height of 8 feet?

• A. 25.12 sq ft
• B. 12.56 sq ft
• C. 18.75 sq ft
• D. 31.41 sq ft

Answer: (A)

Area around the side of a cylinder is found with the lateral surface area formula, which is 2πrh. Here, the radius must be in feet to match the height in feet. Convert 6 inches to feet: 6 inches = 0.5 feet. The height is 8 feet.

Compute the side area: 2π × 0.5 × 8 = 8π square feet. Using π ≈ 3.14 gives 8 × 3.14 = 25.12 square feet.

So the area is about 25.12 square feet, which is the value shown. (If you were asked for total surface area, you’d also include the top and bottom, giving a larger number.)