Question

a solid cylinder of 9cm height and 4 cm in diameter is melted and recasted to form a cone of diameter 6 cm .
Find the height and total surface area of the cone ( take π as 3.14 )​

Answer 1

Answer:

We have

Height of solid circular cylinder= 10cm

Radius of the base = 6cm

volume of the remaining solid = volume of the cylinder - volume of the cone

Volume of remaining solid=(πr  

2

h)−  

3

1

​  

πr  

2

h

={π×6  

2

×10−  

3

1

​  

×π×6  

2

×10}cm  

3

=(360π−120π)cm  

3

=240πcm  

3

 

slant height of the cone

=OC=  

OC  

2

+O  

′

C  

2

 

​  

=  

10  

2

+6  

2

 

​  

=2  

34

​  

cm

Whole surface area = curved surface area of the cylinder + area of the base the cylinder + curved surface area of cone

={2π×6×10+π×6  

2

+π×6×2  

34

​  

}cm  

2

=(156+12  

34

​  

)πcm  

2