Question 1127568
 A lamp shade is in the form of a frustrum of a cone.
The bottom radius is thrice the top radius and the height is 14cm,
If the volume of a lamp shade is 763 cm3., calculate the bottom radius
:
The volume formula of a frustrum: {{{V =1.0472h(R^2 + Rr + r^2)}}}  
In this problem we have
{{{V =1.0472*14(R^2 + Rr + r^2)}}} = 763
the top radius = r
the 
3r = the bottom radius (R)
{{{1.0472*14((3r)^2 + (3r)r + r^2)}}} = 763
:
{{{14.66(9r^2 + 3r^2 + r^2)}}} = 763
:
{{{13r^2 = 763/14.66}}}
:
{{{13r^2 = 52.0464}}}
:
{{{r^2 = 52.0464/13}}}
:
r^2 ~ 4
r = 2 cm is the top radius
then
3(2) = 6 cm is the bottom radius, a very tiny lamp