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Question
A rectangular sheet of paper 40 cm × 22 cm, is rolled to form a hollow cylinder of height 40 cm. The radius of the cylinder (in cm) is ______.
Options
3.5
7
\[\frac{80}{7}\]
5
Solution
A rectangular sheet of paper 40 cm × 22 cm, is rolled to form a hollow cylinder of height 40 cm. The radius of the cylinder (in cm) is 3.5.
Explanation:
We have,
Length of the rectangular sheet, l = 40 cm,
Width of the rectangular sheet, b = 22 cm and
Height of the hollow cylinder, h = 40 cm
Let the radius of the cylinder be r
As, l = h
So, the circumference of base of the cylinder = b
⇒ 2πr = 22
`=> 2xx22/7xx"r" = 22`
`= "r"=(22xx7)/(2xx22)`
∴ r = 3.5 cm
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