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A frustum of a cone has radii 4 cm and 8 cm and height 3 cm. Its slant height is
A4 cm
B5 cm
C7 cm
D12 cm
Answer & Solution
Correct answer: B. 5 cm
1. Slant height l = square root of (h squared + (R - r) squared).
2. = square root of (9 + 16) = square root of 25.
3. = 5 cm.
_Source: NCERT Class 10 Mathematics, Ch 12 "Surface Areas and Volumes", §12.4_
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