30 circular plantes, each of radius 14 cm and thickness 3 cm are placed one above the another to from a cylindrical solid . Find
(i) the total surfce area.
(ii) volume of the cylinder so formed.

Explanation

Given, radius of a circular plate, r = 14 cm
Thickness of a circular plate = 3cm
Thickness of 30 circular plates `= 30xx3 = 90 cm`
Since, 30 circular plates are placed on above the another to from a cylindrical solid. Then,
Height of the cylindrical solid, h = Thickness of 30 circular plates = 90 cm
(i) Total surface area of the cylindrical solid so formed
`= 2 pir (h + r) = 2 xx(22)/(7) xx 14(90 +14)`
`= 44xx 2xx 104 = 9152 cm^(2)`
Hence, the total surface of the cylindrical solid is `9152 cm^(2)` .
(ii) Volume of the cylinder of the cylinder so formed `= pir^(2) h`
`= (22)/(7) (14)^(2)xx 90 = (22)/(7)xx14 xx 14 xx90`
`= 22 xx 28 xx 90 = 55440 cm^(3)`
Hence, the volume of the cylinder so formed is `55440cm^(3)`.