(e) of theseU. The frustrum of a right circular cone has theradii of

1.	(e) of theseU. The frustrum of a right circular cone has theradii of base 4 cm, of the top 2 cm and aheight of 6 cm. Find the volume of thefrustrum.
Answer» External volume =20×12×5=1200cm220×12×5=1200cm2 Internal volume =(20−2)×(12−2)×(5−2)(20−2)×(12−2)×(5−2) =18×10×3=540cm218×10×3=540cm2 Therefore, Volume of the metal = External volume - Internal volume = 1200 - 540 =660cm3660cm3. Volume =πh3(R2+r2+Rr)πh3(R2+r2+Rr) =227×63×(16+4+8)227×63×(16+4+8) =227×2×28=22×8227×2×28=22×8 =176cm3

(e) of theseU. The frustrum of a right circular cone has theradii of base 4 cm, of the top 2 cm and aheight of 6 cm. Find the volume of thefrustrum.

Answer»

External volume

=20×12×5=1200cm220×12×5=1200cm2

Internal volume

=(20−2)×(12−2)×(5−2)(20−2)×(12−2)×(5−2)

=18×10×3=540cm218×10×3=540cm2

Therefore, Volume of the metal = External volume - Internal volume

= 1200 - 540 =660cm3660cm3.

Volume =πh3(R2+r2+Rr)πh3(R2+r2+Rr)

=227×63×(16+4+8)227×63×(16+4+8)

=227×2×28=22×8227×2×28=22×8

=176cm3