A rectangular sheet of dimentions 25 ×7 cm is rotated about its longer side. What is whole surface area then generated
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Hii
The solid so formed is a cylinder of height 25 cm and radius 7 cm and the formula of the total surface area is :
The solid so formed is a cylinder of height 25 cm and radius 7 cm and the formula of the total surface area is :
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shrivastavavina:
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this isn't right
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You have answered for : Rolling the given sheet into a hollow cylindrical pipe..
so I leave it like that.
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Rectangular sheet dimensions = 25 cm X 7 cm.
It is rotated about the edge 25cm. So it forms a 3-d solid. It is a solid cylinder of length (height) h = 25 cm and radius r = 7 cm.
curved surface area CSA
= 2 pi r h
= 2 × 22/7 × 7 × 25 cm^2
= 1, 100 cm^2.
Surface area of two flat sides
= 2 pi r^2
= 2 × 22/7 × 7^2 cm^2
= 308 cm^2
TSA total surface area
= 1,100+308 = 1,408 cm^2
we can also use formula 2 pi r (r+h).
It is rotated about the edge 25cm. So it forms a 3-d solid. It is a solid cylinder of length (height) h = 25 cm and radius r = 7 cm.
curved surface area CSA
= 2 pi r h
= 2 × 22/7 × 7 × 25 cm^2
= 1, 100 cm^2.
Surface area of two flat sides
= 2 pi r^2
= 2 × 22/7 × 7^2 cm^2
= 308 cm^2
TSA total surface area
= 1,100+308 = 1,408 cm^2
we can also use formula 2 pi r (r+h).
:-)
This i the answer for rotating the entire sheet , with holding one edge of 25 cm fixed. So a solid cylinder results after rotation.
This is not the answer for rolling the sheet into a cylindrical pipe.
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