Calculate the surface area of a cylindrical drum of radius 21cm, height 50cm open at the top.

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The surface area of a cylindrical drum of radius 21cm, height 50cm open at the top.

radius R = 21cm

height H = 50cm

bottom surface S = 3.14 x R x R = 3.14 x 21 x 21 = 1385 square cm

bottom circumference BS = 3.14 x 2 x R = 3.14 x 2 x 21 = 132 cm

wall surface area WS = BS x H = 132 x 50 = 6600 square cm

whole outside surface area S + WS = 1385 + 6600 = 7985 square cm

whole inside and outside surface area 2 (S + WS) = 2 (1385 + 6600) = 15970 square cm