Question

a rectangular pieces of paper is 22cm in length and 10 cm in width . it is rolled into a cylinder along its length . find the surface area of this cylinder

Answer 1

Here,length of paper = Circumference = 22 cm
Width of paper = height of cylinder = 10 cm
Then,

Circumference = 22 cm

=> 2πr = 22

=> 2x(22/7) x r = 22

=> r = 7/2 = 3.5 cm

Now,

Curved Surface Area of cylinder = 2πrh

= 2 x (22/7) x 3.5 x 10

= 220 cm²
Total surface area = 220 +2 x (22/7)x 3.5²

= 220 + 77

= 297 cm²

Answer 2

length= 22 cm

height= 10 cm

now,

crcumference = 22 cm

2πr = 22

2x(22/7) x r = 22

r = 7/2 = 3.5 cm

curved surface of a cylinder  = 2πrh

= 2 x (22/7) x 3.5 x 10

= 220 square cm

total surface area = 220 +2 *(22/7)x 3.5*3.5

total surface area =220 + 77

= 297 square cm