Multiple choice

A solid cylinder of radius r and height h is placed over other cylinder of same height and radius. The total surface area of the shape so formed is:

  1. $4 \pi r h + 4 \pi r^2$
  2. $4 \pi r h $
  3. $ \pi r h + \pi r^2$
  4. $4 \pi r h -  \pi r^2$
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A Correct answer
Explanation

Two cylinders stacked: height becomes 2h. Total surface area = 2 * pi * r^2 (top and bottom) + 2 * pi * r * (2h) (side area). This equals 2 * pi * r^2 + 4 * pi * r * h.

AI explanation

Placing one cylinder over another of the same height and radius creates a new cylinder with height 2h and radius r. The total surface area of a solid cylinder is 2 * pi * r * (r + h). Substituting the new height gives 2 * pi * r * (r + 2h), which expands to 4 * pi * r * h + 4 * pi * r^2.

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