Volume 2 : 3 ratio of the volumes of the sphere and cylinder is credited to Archimedes. The volume of a sphere is the integral of an infinite number of infinitesimally small circular disks of thickness "dx". The calculation for the volume of a sphere with center 0 and radius "r" is as follows. The surface area of the circular disk is formula_10. The radius of the circular disks, defined such that the x-axis cuts perpendicularly through them, is or where y or z can be taken to represent the radius of a disk at a particular x value. Using y
The X-Files Region 2, such as "Deadalive", "Existence", "Nothing Important Happened Today", "Providence" and "The Truth". Various other episodes were released on DVD and VHS. In 2005, four DVD sets were released containing the main story arc episodes of "The X-Files". The four being "Volume 1 Abduction", "Volume 2 Black Oil", "Volume 3 Colonization" and "Volume 4 Super Soldiers". A boxed set containing all nine seasons and the first film was made available in 2007, which contains all of the special features from the initial releases. The set also includes an additional disc of new bonus features and various collectibles, including a