Question

An 18cm long iron pipe has an external diameter 24cm . If the thickness of the pipe is 1cm. Find the total surface area of the pipe.​

Answer 1

Now, Total surface area = Area of both ends +

Curved surface area

Now area of both ends =2(Area of one end)

Now external radius is equal to 24/2=12cm

Now we know thickness of pipe = 1 cm

Therefore internal radius = 11 cm

Therefore area of one end π(12^2-11^2)

=π×12-11×12+11

=23π

Area of both ends =23π×2

=46π

Area of inside curved surface area =2πrh=2π×11×18 = 396π

Area of outer curved surface area=

2π×12×18=432π

therefore total area is equal to 432π+396π+46π=874π = 2746.8 cm^2