# A rectangular sheet of paper 21 cm X 14 cm is rotated about its breadth, find the curved surface area and the total surface area of the cylinder so formed?

We have : A rectangular sheet of paper 21 cm $×$ 14 cm
And as given  : rectangular sheet of paper is rotated about its breadth , So from this information we know

Height of formed cylinder  =  Breadth  =  14 cm
And
Radius of base  = 21 cm

We know curved surface area of cylinder  =
So,
Curved surface area of formed cylinder  =
And
Total surface area of cylinder =  curved surface area  +  2 (  area of circular base )

So,

Total surface area of cylinder =  curved surface area  +  2 (  )

Total surface area of cylinder =  1848 +

Total surface area of cylinder =  1848 +

Total surface area of cylinder =  1848 + 2772

Total surface area of cylinder =  4620  cm2                                   ( Ans )

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Since 14 cm is the breadth, therefore it will be the height of the cylinder formed. And 21cm will be the circumference of the circle. So the using the formula of circumference of circle that is 2*pie*r = 2*22/7*r= 21. Therefore, r= 21*7/2*22. And then u get the height and you get the radius. Then use the formula of tsa abs CSA and you'll get your answer. Hope this helps.
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