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प्रश्न
The length of the longest pole that can be kept in a room (12 m × 9 m ×8 m) is
विकल्प
144 cm2
216 cm2
180 cm2
108 cm2
उत्तर
216 cm2
Let the edge of the cube be a cm.
Then, length of the diagonal `=sqrt(3"a")`
or,
`sqrt(3"a") = 6sqrt(3)`
⇒ a = 6 cm
Therefore, the total surface area of the cube = 6a2
`= (6xx6xx6) "cm"^3`
= 216 cm3
Therefore, the total surface area of the cube = 6a2
= (6 × 6 × 6 ) cm3
= 216 cm3
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Assertion (A)
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Reason (R)
The total surface area of a hemisphere is 3π r2.
- 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.
