Question

can you answer me of 7 and 8 its too hard

Answer 1

So first of all Hypotenuse of traingle is necessarily 13.
Now talking of base
How to decide which side should be taken as base
So here's what u will do
Base is the side which is revolved
So in first case 12 is the base and then follow the attachment
NOW FOR THE 8TH SUM
U just switch 5 and 12
i.e Now 5 becomes side because that's the side revolved now
and h=12
Now again use the formula
V=πr^2*(h/3)
and get the value
Hope it helps
:)