why isit posible to calculate the volume of a skewed prism or oblique cylinder with the same formula as the euation for the volume of a right prism or cylinder?

The volume of oblique cylinders is the same volume as a right cylinder of the same radius and height. The height of cylinder must be the perpendicular height, but as long as the radius and height are the same the volume does not change, which is why the same formula can be used for both oblique and right cylinder.

For skewed and right prism, base length and height does not change, volume for both is calculated by area times height.