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प्रश्न
Assertion (A)
The curved surface area of a cone of base radius 3 cm and height 4 cm is 15π cm2.\
Reason (R)
Volume of a cone = πr2h
- Both Assertion (A) and Reason (R) are true and Reason (R) is a correct explanation of Assertion (A).
- Both Assertion (A) and Reason (R) are true but Reason (R) is not a correct explanation of Assertion (A).
- Assertion (A) is true and Reason (R) is false.
- Assertion (A) is false and Reason (R) is true.
उत्तर
Assertion (A) is true and Reason (R) is false.
Assertion (A):
Curved surface area of a cone `=pisqrt("r"^2 + "h"^2 )`
`= pixx3xxsqrt((3)^2 + (4)^2)`
`=pixx3xxsqrt(9+16)`
`=pixx3xxsqrt(25)`
= 15 π cm2
Hene, Assertion (A) is true.
Reason (R): The given statement is false.
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संबंधित प्रश्न
Due to heavy floods in a state, thousands were rendered homeless. 50 schools collectively offered to the state government to provide place and the canvas for 1500 tents to be fixed by the governments and decided to share the whole expenditure equally. The lower part of each tent is cylindrical of base radius 2.8 cm and height 3.5 m, with conical upper part of same base radius but of height 2.1 m. If the canvas used to make the tents costs Rs. 120 per sq. m, find the amount shared by each school to set up the tents. What value is generated by the above problem? (use `pi =22/7`)
Find the number of coins, 1.5 cm is diameter and 0.2 cm thick, to be melted to form a right circular cylinder of height 10 cm and diameter 4.5 cm.
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A right triangle whose sides are 15 cm and 20 cm (other than hypotenuse), is made to revolve about its hypotenuse. Find the volume and surface area of the double cone so formed. (Choose value of π as found appropriate)
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The length of the longest pole that can be kept in a room (12 m × 9 m ×8 m) is
How many solid cylinders of radius 6 cm and height 12 cm can be made by melting a solid sphere of radius 18 cm?
Activity: Radius of the sphere, r = 18 cm
For cylinder, radius R = 6 cm, height H = 12 cm
∴ Number of cylinders can be made =`"Volume of the sphere"/square`
`= (4/3 pir^3)/square`
`= (4/3 xx 18 xx 18 xx 18)/square`
= `square`
The volume of a sphere is 4851 cm3. Its diameter is ______.
Find the surface area of a sphere of radius 7 cm.
Solution :
The surface area of the sphere = 4πr2
= `4 xx 22/7 xx square^2`
= `4 xx 22/7 xx square`
= `square xx 7`
∴ The surface area of the sphere = `square` sq.cm.
