Maybe you could try to search on the already asked questions. There is probably one thread that fits more or less your question. Maybe here : http://www.mathhelpforum.com/math-he...-question.html, or here : http://www.mathhelpforum.com/math-he...lume-cone.html. Check out there : http://www.mathhelpforum.com/math-he...earchid=263138. Good luck.