The volume of a right circular cone is 12936 cubic cm and its height is 28 cm. What is its curved surface area, in square cm? (Use π = 22/7.)

(1/3)π$r^{2}h=12936$ gives (1/3) $\times (22/7)x{r}^{2}x$ 28 = 12936, so $r^2=441$ and $r=21$ cm. The slant height is $l$ = √$(21^2+28^2)=$ √1225 = 35 cm, so the curved surface = π$rl=(22/7)\times 21\times 35=2310$ sq cm. The trap 1848 uses the height 28 cm in place of the slant height 35 cm; 3696 adds the base π$r^2=1386$ sq cm, giving the TOTAL surface rather than the curved one; 4620 uses 2π$rl$, a cylinder's formula.