Page 2 - IX Math CBQ ch-11 Surface area

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incurred while cutting, amounts to approximately 1 m , find the volume of the tent that can
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be made with it.
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11 Assertion (A): If a ball is in the shape of a sphere has a surface area of 221.76 cm , then its
diameter is 8.4 cm.
Reason (R): If the radius of the sphere be r , then surface area,

12 Assertion (A): Total surface area of the cylinder having radius of the base 14 cm and height 30 cm
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is 3872 cm .

Reason (R): If r be the radius and h be the height of the cylinder, then total surface area = (2πrh +
2
2πr )

13 Assertion (A): If the radius of a cone is halved and volume is not changed, then height remains
same.

Reason (R): If the radius of a cone is halved and volume is not changed then height must become
four times of the original height

14 Assertion (A): The number of coins 1.75 cm in diameter and 2 mm thick is formed from a melted
cuboid 10cm × 5.5cm × 3.5cm is 400.

Reason (R): Volume of a cylinder =πr 2h cubic units and area of cuboid = (l × b × h) cubic units.

15 Mathematics teacher of a school took her 9th standard students to show Gol Gumbaz. It was
a part of their Educational trip. The teacher had interest in history as well. She narrated the
facts of Gol Gumbaz to students. Gol Gumbaz is the tomb of king Muhammad Adil Shah, Adil
Shah Dynasty. Construction of the tomb, located in Vijayapura , Karnataka, India, was started
in 1626 and completed in 1656. It reaches up to 51 meters in height while the giant dome has
an external diameter of 44 meters, making it one of the largest domes ever built. At each of
the four corners of the cube is a dome shaped octagonal tower seven stories high with a
staircase inside.

(a) What is the total surface area of a cuboid?
(b) What is the curved surface area of hemispherical dome ?

d) What is the circumference of the base of the dome ?

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