I've done maximization problems before but I'm finding this one though because there're no numbers to work with and when I think I'm getting somewhere I get all confused. I would really apreciate some help.

Thanks...

...A sector is removed from a circular disk of radius L and subsequently the two radial edges of the remainder of the disc are joined together to form a right circular cone. Find the angle of the cut-out sector that maximizes the volume of the cone..."