We have -2 π h (R-r) = 132 = 2×22/7×21(R-r) =132 R-r = 1 Also given – R + r = 21 Then – R = 11cm, r = 10cm. So, the total surface of the hollow cylinder = 2 π h(R-r) +2 π (R2-r2) =2 π (R +r) [h +R-r] =2×22/7×21(21+1) =6×22×22 =2904cm2
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