Example 11 A rectangular piece of paper 11 cm × 4 cm is folded without overlapping to make a cylinder of height 4 cm. Find the volume of the cylinder.
Also,
Length of rectangle = 11 cm
Breadth of rectangle = 4 cm
Since rectangle is rolled along its width to make cylinder
Height of cylinder = Width of rectangle = 4 cm
Let r be the radius of the cylinder.
Now, since rectangle is rolled to become cylinder
∴ Perimeter of bottom of the cylinder = Length of the rectangle
Circumference of circle = 11
2πr = 11
2×22/7×𝑟 = 11
44/7×𝑟 = 11
𝑟 = 11 × 7/44
𝑟 = 7/4
Now,
Volume of cylinder = 𝜋𝑟^2 ℎ
= 22/7×(7/4)^2×4
= 22/7×7/4×7/4×4
= (22 × 7)/4
= 154/4
= 77/2
= 38.5 cm3

Made by

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths and Science at Teachoo.