If the total surface area of a hemisphere is 27π square

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If the total surface area of a hemisphere is 27π square cm, then the radius of the base of the hemisphere is

If the radius of hemisphere be r cm,
then 2πr² + πr² = 27π
⇒ 3πr² = 27π
⇒ 3r² = 27
⇒ r² = 9
∴ r = 9 = 3 cm