Question

What is the CSA of "HOLLOW " cone and frustum(plz dont ignore this HOLLOW word)
In HOLLOW figure case are different)
Also in the que dont ignore this HOLLOW word(in hollw there would be 2 radius in frustum there will be 4 and 2 different slant height in cone 2 different height) solve this HOLLOW prob

Answer 1

Answer:

Step-by-step explanation:

bro... curved surface area for any hollow geometric figure is divided into 2 parts:    external CSA and internal CSA

Let the thickness be x

In case of frustrum:

External CSA: πl(r1 + r2)

Internal CSA: πl(r1-x+r2-x)

In case of cone:

External CSA: πrl

Internal CSA: π(r-x)l

ATP

πl(r1 + r2)=8/9*π(r2)l

l(r1 + r2)=8/9*(r2)l