Question

The altitude of a circular cylinder is increased six times and the base area is decreased
one-ninth of its value. The factor by which the lateral surface of the cylinder increases, is​

Answer 1

Answer:

Step-by-step explanation:

Curved surface area of cylinder =2πrh

Height is increased to 6 times =6h

Base area is decreased to (  

9

1

​  

th)  

i.e. π(r  

′

)  

2

=  

9

1

​  

πr  

2

⇒r  

′

=  

3

1

​  

r

Now,

New curved surface area =2π×  

3

1

​  

r×6h

                                          =2×(2πrh)

∴  Lateral surface area becomes twice.