Question

a rectangular sheet paper40cmx 22cm is rolled to form a hollow cylinder of height 40cm. find the radius ofthe cylinder​

Answer 1

Answer:

r = 3.5 cm

Step-by-step explanation:

Given:

Length of the rectangle = 40 cm

Breadth of the rectangle = 22 cm

It is given that the rectangular sheet is used to make a hollow cylinder
∴ Area of rectangle = Curved surface area of a cylinder

Area of rectangle = l x b

                             = 40 x 22

                             = 880 cm²

Hence the curved surface area of a hollow cylinder will be 880 cm²

Now, Length of rectangle = height of the cylinder

We know that,

CSA of cylinder = 2πrh
                  880 = 2 x (22/7) x r x 40

                    (880 x 7) / (2 x 22 x 40) = r

                           ∴ r = 3.5 cm

Answer 2

Answer:

3.5cm

Step-by-step explanation:

2πr=22cm ie base

r= 22/2π=3.5cm