Cylinder Total Surface Area | Exercise 13.2 | Q2

Class 9 Maths | NCERT Solution to Exercise | Surface Areas & Volumes

Question 2: It is required to make a closed cylindrical tank of height 1 m and base diameter 140 cm from a metal sheet. How many square metres of the sheet are required for the same?


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Explanatory Answer

The tank required to be made is a closed cylindrical tank. Therefore, the top of the cylindrical tank will be closed.
The area of sheet metal required to make the tank will include the base area and the area of the top. i.e., we have to compute the total surface area of the cylinder.

Total surface area of a cylinder = 2 × π × r × (h + r)
Height = 1 m
Base diameter = 140 cm. So, base radius = 70 cm
Convert base radius to m. Base radius = \\frac{70}{100}) m = \\frac{7}{10}) m

Take π =\\frac{22}{7})
Total surface area = 2 × \\frac{22}{7}) × \\frac{7}{10}) × (\\frac{7}{10}) + 1)
= \\frac{44}{10}) × \\frac{17}{10})
= \\frac{748}{100})
Or total surface area = 7.48 m2
7.48 m2 of sheet metal is required to make the cylindrical tank.

 


NCERT Solutions for Class 9 Math | Chapter 13 Video Solutions



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