2018 · Q79
A solid right cylinder is of height π cm. If its lateral surface area is half its total surface area, then the radius of its base is
Elementary MathematicsMensuration
- Aπ/2 cm
- Bπ cm
- C1/π cm
- D2/π cm
Explanation
Lateral area 2 pi r h is half the total area 2 pi r h + 2 pi r^2, so 2 pi r h = pi r h + pi r^2, i.e. r h = r^2. Thus r = h = pi cm. Hence option B.