What is the surface area of a right circular cylinder with radius 2 and height 5 (expressed in terms of pi)?

• A. 28 pi
• B. 16 pi
• C. 30 pi
• D. 20 pi

Answer: (A)

The surface area of a right circular cylinder comes from two parts: the curved side and the two circular ends. The curved side has area equal to the circumference of the base times the height, which is 2πr times h. The two ends contribute the combined area 2πr^2 (one πr^2 for each end). So the total surface area is SA = 2πrh + 2πr^2.

Plugging in r = 2 and h = 5:

• Lateral area: 2πrh = 2π·2·5 = 20π

• Ends: 2πr^2 = 2π·(2)^2 = 8π

Add them: 20π + 8π = 28π.

Therefore, the surface area is 28π. Common missteps include forgetting to include both bases or miscomputing the lateral area, which would lead to smaller or larger values.