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Question
A solid frustum is of height 8 cm. If the radii of its lower and upper ends are 3 cm and 9 cm respectively, then its slant height is
Options
15 cm
12 cm
10 cm
17 cm
Solution
`r_1 = 9 "cm"`
`r_2 =3 "cm"`
`h = 8"cm"`
Slant height of frustum , l `=sqrt(h^2 + (r_1 - r_2)^2)`
`= sqrt(8^2 + (9 - 3)^2)`
`= sqrt(64 + 36)`
`= sqrt 100`
`= 10 "cm"`
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