A rectangular sheet of dimensions 20 cm x 7 cm is rotated about its longer side. Find the volume and
the total surface area of the solid thus generated.
A hollow cylindrical copper pipe is 21 m long. Its outer and 'inner diameters are 10 cm and 6.0
respectively. Find the mass of the copper used in making the pipe if mass of 1 cm copper is abon
9g. ao
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Answer:
When a rectangular sheet is rotated about its length, we get a cylinder
where the height of cylinder =7 cm
and the circumference of the base of the cylinder =25 cm
Thus curved surface area =2πrh
=(2πr)×h
=25×7
=175 cm
2
Step-by-step explanation:
Hope
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