50 circular plates each of radius 7 cm and thickness 5 mm are placed one above another to form a solid right circular cylinder. Find the total surface area of the cylinder so formed.

Answer

`1408 cm^(2)`.

Explanation

Clearly, we have
radius of the cylinder so formed, r=7 cm, and
height of the cylinder so formed, `h=(50 xx 5) m m`
`=250 m m = 25 cm`.
`:." total surface area of the cylinder so formed "`
`=2pir(h+r)=[2xx22/7xx7xx(25xx7)]cm^(3)`
`=(2xx22xx32)cm^(2)=1408 cm^(2)`.