NCERT Class 9 Solutions: Surface Areas and Volumes (Chapter 13) Exercise 13.2 – Part 1
Q1 The curved surface area of a right circular cylinder of height is . Find the diameter of the base of the cylinder.
Solution:
The radius of the base is and the height of the cylinder. Therefore, curved surface area of cylinder

(Given)




So, the diameter of the base is =
Q2 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?Solution:
We are given that diameter of base and Height
Therefore, metal sheet required to make a closed cylindrical tank =
Q3 A metal pipe is long. The inner diameter of a cross section is , the outer diameter being (see Fig.). Find its

Inner curved surface area,

Outer curved surface area,

Total surface area.
Solution:
External radius is and the internal radius is the length of the pipe is , therefore

Inner curved surface


Outer curved surface


( )



Total surface area of a pipe = Inner curved surface area + outer curved surface area + areas of two base


( )

