mathssurface area
posted by anoynomous .
A cone 7dm high and 6 dm in diameter is placed on the ground. Sand is poured over it until conical heap 21 dm high and 33 dm circumference at the bottom is formed. Find how many m^3 of sand is there?

volume of cone is 1/3 pi r^2 h
subtract the small cone from the large cone
That's how much is sand. 
what about 33dm circumfernce

what about 33dm circumfernce

well, you know that C = 2pi r, so,
r = 33/2pi
Forgot about that?