Question

Find the volume of this cylinder.

Answer 1

Volume of a Right circular cylinder=πr²h

Using "Cavaliers principle" or Just pire logic... it can be understood that...

if we were to cut of the base and top of the cylinder such that it will make up to be a right circular cylinder and join the other two pieces on top; We would obtain a Right circular cylinder With The same radius and height as the Given cylinder.

So;

Given. Base area B=81πcm²

also Base area =πr²

=>πr²=81π cm²

=>r=√81=9cm

Also Given;

Height h=3r

=>Height,h=3×9=27cm

So;Volume of cylinder V=πr²h ;(r²=81,h=27)

=>V=(81×27×22)/7

=>V=6867.18cm³ (approx.)

So,Required Volume =6867.18cm³(approx.)

Hope it helps...

Regards,

Leukonov/Olegion.