Mohan lives in Hyderabad in Telengana. Those were very hot days of May. He thought that if we
human beings need so much water to drink, wont the birds also be thirsty. He decided to
prepare a vessel to provide water for birds. He found a flexible blue coloured plastic rectangular
sheet 41cm x 15cm. He rolled it along its length and joined the opposite ends using a tape. He
wanted to have a circular base for this cylinder and searched for another cylinder. He found a
square sheet 15cm x 15cm. He cut a circular sheet just equal to the base of the cylinder from it.
Now answer the following questions:
a) The curved surface area of the cylinder formed is:
i. 540 cm2
ii. 560 cm2
iii. 640 cm2
iv. 660 cm2
b) The radius of the base of the cylinder is:
i. 2 cm
ii. 3.5 cm
iii. 7 cm
iv. 10 cm
c) The radius of the circular base required for cylinder is
i. 154 cm
ii. 216 cm
iii. 260 cm
iv. 308 cm
d) How much will be the area of square sheet left unused after removing the circular base of
the cylinder from it?
i. 69 cm2
ii. 71 cm2
iii. 83 cm2
iv. 91 cm2
Answers
Answer:
a) The curved surface area of the cylinder formed is:
iii. 640 cm2
b) The radius of the base of the cylinder is:
b) The radius of the base of the cylinder is:i. 2 cm
c) The radius of the circular base required for cylinder is
iii. 260 cm
d) How much will be the area of square sheet left unused after removing the circular base of
d) How much will be the area of square sheet left unused after removing the circular base of the cylinder from it?
i. 69 cm2
Answer:
CSA=660cm^2, Radius= 7cm, a=154cm, Unused Area=71cm^2
Step-by-step explanation:
To find CSA we need radius so that to find radius we use formula of circumference of circle(base of cylinder)
l=2πr
41=2×3.14×r
r≅7cm ------------------------------------(i)
therefore
(a) curved surface area of circle=2πrh (h=height of cylinder)
=2×3.14×7×15
=660cm^2
(b)Radius of the base of cylinder = 7cm {from (i)}
(c)Area of circular base of cylinder=πr^2
=3.14×7×7
=154
(d)Unused area = (area of square sheet)-(area of circular base of cylinder)
=(15×15)-(154)
=225-154=71 cm^2