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Question
Assertion (A)
If the radii of the circular ends of a bucket 24 cm high are 15 cm and 5 cm, respectively, then the surface area of the bucket is 545π cm2.
- Reason(R)
If the radii of the circular ends of the frustum of a cone are R and r, respectively, and its height is h, then its surface area is - Both Assertion (A) and Reason (R) are true and Reason (R) is a correct explanation of Assertion (A).
- Assertion (A) is true and Reason (R) is false.
- Assertion (A) is false and Reason (R) is true.
Solution
Assertion (A):
Let R and r be the top and base of the bucket and let h be its height.
Then, R = 15 cm, r = 5 cm and h = 24 cm
Slant height, `"l" = sqrt("h"^2 + ("R"- "r")^2`
`=sqrt((24)^2+(15-5)^2)`
`= sqrt(576 + 100)`
`=sqrt(676)`
= 26 cm
Surface area of the bucket = π [R2 + r2 + l(R+r)]
`= pixx[(15)^2 + (5)^2+26xx(15+5)]`
= π ×[225 + 25 + 520]
= 770 π cm2
Thus, the area and the formula are wrong.
Notes
Question seems to be incorrect.
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