Question

The radii of the ends of a frustum
of a cone 45 cm high are 28 cm and 7 cm
(see Fig. 13.21). Find its volume, the curved
s u r f a c e a r e a a n d t h e t o t a l s u f a c e a r e a

Answer 1

@marimar @magenxoxo

Answer 2

@timo86m

Answer 3

@Jenn777 HELP

Answer 4

@bngaure @nincompoop

Answer 5

not sure

Answer 6

now,
R/H=r/(H-h)
=>Hr=HR-hR
=>hR=HR-Hr=H(R-r)
=>H=Rh/(R-r)=28(45)/(28-7)=28(45)/21=4(45)/3=4(15)=60cm
and,
l=sqrt(r^2+h^2)=sqrt(7^2+45^2)
L=sqrt(R^2+H^2)=sqrt(28^2+60^2)
so,
V=(1/3)[piR^2-pir^2]h
=(pi*h/3)(R^2-r^2)
Sc=pi(R-r)l
St=Sc+pi(R^2+r^2)

You evaluate yourself.