To our presentationTopic:-surface area of

right circular cylinder and hollow cylinder

What is Cylinder ?What is Hollow Cylinder ?• A solid generated by the revolution of a rectangle about one of its sides is called right circular cylinders.• A solid bounded by two coaxial cylinders of the same height and different radii is called a hollow cylinder

Defination of some terms on the figure of cylinder:-Base:-each of the circular ends on which the cylinder rests is called base.Radius:-the radius of the circular base is called the radius of the circle.Height:-the length of the cylinder is called the height of the cylinder.

CSA of a Cylinder• Curved surface area of the cylinder • =Area of the rectangle• =Area of a rectangle of length2πr and breadth h• =2πr x h square units• =2πrh square units

2πr

h

TSA of a Cylinder• Total surface area of the cylinder• =CSA of cylinder + area of bases• =2πrh + 2 x πr2

• =2πrh + 2πr2

• =2πr(h + r)

2πr

h

πr2

πr2

CSA of a Hollow Cylinder• Let R & r be the external &internal radii of

a hollow cylinder & h be its height as shown fig. 19.7. Then we have the following results:

• Curved(lateral) Surface Area • = External Surface Area + Internal Surface

Area • = 2 xπRh + 2 x πr h• = 2πRh + 2πr h• = 2πh( R + r )sq. units

TSA of a Hollow Cylinder• Let R & r be the external &internal radii of a

hollow cylinder & h be its height as shown fig. 19.7. Then we have the following results:

• Each base Surface area = π(R² - r²) sq. units• Total Surface Area= External Surface Area + Internal Surface Area+

base Surface area= 2 x πRh + 2 x πr h + 2 x π(R² - r²) =2πRh + 2πr h + 2π(R² - r²) = 2π(R +r )h + 2π(R + r) (R - r) = 2π(R + r) ( h + R - r) sq. units

1. A right circular cylinder has base radius 14 cm,and height 21cm.find1) area of base or area of each end.2) curved surface area

2. The total surface area of a cylinder is 231 cm2. Its curved surface is 2/3 of the total surface .Determine the radius and of its base and height

1. A hollow cylindrical pipe has inner circumference 44 dm and outer 45 dm .find the cost of painting it from both sides at Rs 2 per m2, if its length is 3.5m

2. The total surface area of a hollow cylinder ,open at both ends of external radius 8cm and height 10 cm is 338π.taking r to be inner radius ,,find the thickness of the metal of the cylinder

One who asks doubts remains a fool for for minutes one who does’t ask remain a fool for ever- rahul Thank You for watching our

presentationGroup members:-Sankalp R Angadi

Rahul RSudendra R Sam RichardManikanta